Cheat a friend? shouldn't it be "cheat on a friend"?

I also want to point out this is song lyrics from “Careless Whisper” by Wham!

Guilty feet have got no rhythm. Excellent song lyric. Not used elsewhere.

If you cheat a friend then you are swindling them, or stealing from them. To cheat \*on\* a friend is to do something like hang out with people they don't like, or whatever.

Cheating and cheating on have different meanings.

Fun fact: You can also refer to someone as a cheat. “You’re a cheat!”

Just to tack on to the other responses: while "cheat on \[person\]" specifically has sexual relationship connotations, it is sometimes used metaphorically in humor. Example being \[context: you play Chess with this person regularly\] "I saw you playing chess in the park yesterday. Are you cheating on me?" and 'to cheat on \[relationship partner\] with \[affair partner\]' is the structure However, "cheat in/on \[non-person\]" is a structure used for activities which you are 'in'/'on' respectively when participating in them. For example, you can cheat in Poker, and you can cheat on Call of Duty (the video game). You also can 'cheat at \[activity\]', which is effectively a shortened version of "cheat at doing \[activity\]" Lastly, you can "cheat \[requirement\]", which is to slightly violate the requirement for advantage. For example, if you stop a few inches/feet ahead of the starting line in a race when lining up, then you are "cheating the starting line". If you cut just inside the arc of a corner, you are "cheating the corner". The 'requirement' doesn't have to be a serious one, nor does how you 'violate' the requirement have to violate the spirit. You can 'cheat the job time' by having all your materials and workers already on-site and by doing prep work before the time period starts, though that's an uncommon and non-serious form.

a good way to remember this is the expression "cheat death", meaning you deceive death (i.e. you are still alive)

Aside from the proper explanation, you should be wary that often times, lyrics do not follow grammar rules

And waste the chance that I'd been given

To "cheat on" someone refers to infidelity in a romantic relationship. To "cheat" someone means to deceive someone, usually in the sense of not keeping to an agreement made with them. For example, if A and B make a business deal and agree to split the profits 50/50 but then A lies to B about how much money was made so that they can keep more than their fair share, then A is cheating B.

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Cheating someone means treating them unfairly to get an advantage over them. Cheating on someone means being sexually unfaithful to them.

"To cheat someone" is different from "to cheat on someone". The former implies swindling them or tricking them out of something. The latter implies infidelity.

Yes. It's grammatically wrong. Is this George Michael, "Careless Whisper"? Lyrics are anathemic to grammar.

On top of the semantics this is also a lyric which doesn’t follow the rules so much anyway. But no matter what happens in the situation I know that I don’t think I’m ever going to be able to dance with you ever again. And I’m probably never ever going to feel the way I felt with you.

I'm a Gen Z swiftie, but Careless Whisper is the first 80s/90s song that I love! Pop songs nowadays are ruining the music taste of our generation! I am thinking of abandoning Taylor's music at this point.

tonight the music seeeeems so loud

Songs don't have to follow rules of grammar, pronunciation or any other language rules, and often don't. It's called "Poetic license" and basically you can do what you want if it sounds good and fits in with the song or poem.

I could write several paragraphs on this (and if you want that, let me know), but the short answer is: “Cheat a friend” fits lyrically better than “cheat on a friend.” The latter phrase is too wordy to fit with the line the way it’s written. A possible alternative could be: “should’ve known not to cheat on a friend.”