Do you use inversion in everyday conversation?

The answer is probably what you'd expect: no, these features aren't frequently used in colloquial native speech. Yes, you will still encounter them sometimes in colloquial native speech. No, there's no general rule as to when you should expect to encounter them or not. Yes, it's down to individual speech patterns which are completely idiosyncratic and largely unpredictable.

I mean, it's not common, but I would not be surprised to hear someone say either of your examples. Although the first one would sound more normal to me if you added "or what" on the end/"ever" after "did i" for emphasis

So personally, I use this format of speaking so frequently or at least comfortably, I never would have thought to label it and separate it out as a stylistic choice. I definitely hear it commonly enough that it doesn’t sound weird, antiquated, or like a specific dialect. Not everyone speaks that way, but definitely everyone has heard people speak that way. Examples of ways I might personally phrase things: “Trump was on CNN this morning and, oh man, did he look like a freakin’ moron. Again.” “Had I known you were coming, I would have baked brownies!” “Were I a smarter person, I would have left my keys on this hook….like I am supposed to. But I am not a smarter person, evidently, and I cannot find them anywhere!” “Boy, did I need sleep last night! Thank you for not waking me up when I accidentally fell asleep in the middle of the movie. I feel so well rested today!”

I use the "Had I..." structure very often. Maybe not every day, but at least every week. Some people use different grammar more than others. Some people use different vocabulary than others. It comes down to personal preference, education level, and dialect.

I don't know the term 'inversion', but for each situation, both of your examples sound fine. I would have thought that in this context "Did I say something dumb!" was a 'rhetorical question', meaning 'I recognise that I said something dumb." And the traffic one just seems like we're omitting the the "If" in a conditional statement. Both seem fine to me, although they don't seem to be the same sort of thing to me. (Perhaps 'inversion' refers to some uniting principle that I'm not recognising though.)

I think I do - but I'm not sure I fully understand what you're asking. Do I use this sentence constructing: "If I had...., I'd have..." Sure. Absolutely.

I mix this in for variety sometimes. I... get bored of saying things the same way all the time.

Your first example is not common at all. But “had I X, I’d have Y” is quite common. The real answer is, some constructions are very common and others are not at all. You’d be understood either way, but some inversions are so uncommon that it would sound forced or old-timey.

As others have pointed out, "Had I known... I'd have..." is pretty common. The other is less so, but tends to come up in oral storytelling more often, as a way of building suspense. "[     ] happened, and man, did I say something dumb..." and then you have your audience wanting to know what you said, which, when you tell them, acts as a "punchline."

If you say "Ugh, did I say something dumb" with a normal/level tone, this reads as a question from "did" being at the front of the sentence. If you speak it like this: "Ugh, *DID I SAY* something dumb!" then it's a statement with a bunch of exclamation points on "did I say" For a medium level of emphasis you'd say "Ugh, I *did* say something dumb" For a normal level of emphasis you'd say "Ugh, I said something dumb" The stressing with your voice and emphasis on *DID I SAY* makes it clear in spoken language that you're making a statement and not asking a question. In writing it wouldn't be as immediately recognizable as to what it is doing so you'd definitely have to use the exclamation point with it. This pattern with *DID PERSON VERB* would be casual speech and only be used in speaking or written dialogue in a book. I don't think people would write this. When your title said "inversion" my mind immediately went to a sentence like this "Because I got a flat tire, I was late today" or "Since he won the lottery, he quit his job" or "Having already eaten, I won't be needing to join you for dinner" (which are the type of your second example). These are normal things to do or say, although they may sound a shade or two 'fancier' than normal and some people might get irked about this, like you're intentionally talking in a complicated way or it could be harder to follow when the phrases get longer. Because they go against the typical order we hear sentences in, doing this puts the focus on the phrase that goes first (see what I did here). If you're talking to someone and do this with most of your sentences it would get annoying to listen to.

I certainly use such constructions and I have no reason to think other people are any different, No, it is definitely not "just formal"

Inversion is used more frequently in writing because it's great for emphasising. However, if you're a young person trying to fit in with other young native speakers of English, I would avoid using it in conversation. Inversion sounds quite formal and old-fashioned, and it's becoming less popular with younger people, so you may sound strange using it as a non-native speaker.

“Had I…” is not very common. The more usual construction is “If I knew, I would have…” “Had I” is also the subjunctive case which hardly anyone uses, and fewer people call it that or know the grammatical rules for it.

You might be getting misleading answers because people don't fully understand the breadth of sentences that are inverted. Never before have I seen such conflicting answers. Not only is it something we do often in writing, it's something we do quite commonly in speech. In no way are these constructions only literary. Only if we give more examples will people hopefully see that inversion is actually very, very common. I hope you see what I've done here :) [Looking at this list,](https://test-english.com/explanation/b2/inversion-negative-adverbials/) I would say only the ones in red ("Scarcely could I believe...") are used mostly in writing. This isn't even mentioning that inversion is common simply when we ask any questions, or say sentences as simple as "Beside the bed was a lamp". Or in a book: "My name is John," said John.

Do i use it? Yes. Often? No. The example of "ugh, did I say say something dumb!" Actually sounds really old fashioned. Its something I'd expect to hear on an old sitcom. So this one in particular, no i don't really use it. "Had i known" i would say i do use occasionally, but I'm always angry or serious. Its more formal sounding. Lighter: if I had known about the traffic I would have gone to work the other way! At least I made it in time for my shift. More serious: I'm so sorry. Had i known about the traffic i would have left earlier and taken my alternate route to work. I'll plan more carefully next time.

This is slightly different from your question, but I usually think of inversion for forming questions, because in French, using inversion in a question is considered formal. I’ve been spending my days (living in France) forcing myself not to use inversion for questions, so it’s been on my mind. In English, inversion for questions is the expected format. For example, “we’re going to the movies, are you coming?” You could make this more informal by saying, “we’re going to the movies, you coming?”, but if you said, “we’re going to the movies, you’re coming, right?” that wouldn’t make it even more informal, it’d make it passive-aggressive. To your question, “Did I say something dumb!” would require emphasis on I and dumb and without the rising intonation that signals a question to be understood properly, but on its own, this tends to be formal or literary. However, it could be common as a clause in a sentence, like “I saw my teacher at the market on Saturday and boy oh boy, did I say something dumb!” As others have said, the “had I…” construction is in fact very common.

Context matters too , this type of communication often gets used by passive-aggressive and/or condescending people frequently, although not exclusively. Also, it is used for rhetorical questions/statements, too.

To me (Native UK english in my 50s), 'had I...' sounds slightly more formal, and therefore might indicate irritation or mild anger. I would normally say 'if I'd...' Eg, If somebody told me 'If I'd known you were coming I'd have made more food' then I'd just hear that as a statement. If they said 'Had I known you were coming I'd have made more food' (or even 'I would have made more food') then I might wonder if they were a bit cross with me. But this would also be very contextual and would depend on the tone of voice and on the person speaking (some people are just always more formal). Of the two constructions I'd say that 'If I'd...' is more common in the UK and is generally more neutral in tone. Older and more socially reserved or academic people may use 'Had I...' more. But it's a subtle thing, probably varies in other countries, and if I knew someone had learnt english as a second language I probably wouldn't read that meaning into it.

Not common, and requires inflection. Your first example, "Did I say something dumb!" is really a question. You might hear somebody say that as a statement but the tone of the delivery is important. It must be said with a sarcastic tone, and probably delivered with something preceding it or following it like, "Boy, did I say something dumb!" or perhaps, "Did I say something dumb or what?" to emphasize the sarcasm.

I actually think inversion is relatively common. “had I known…I would have…” is something I say regularly. For example: “had I known you were running late, I wouldn’t have waited for you to eat dinner” or “had I known you like cake, I would have saved you a piece!”

Yeah, all the time! It’s a very typical English speech pattern