I suppose this comes down to how you define the phrase in question. The Urban Dictionary lists two dozen meanings of the phrase; the one I'm using for this answer is #7 there:
A socially unacceptable deed or act.
This one might be a little too sophisticated, depending on your audience, but there's the adjective inappropriate:
Please don't do that prank to him. That would be inappropriate.
Macmillan says the word is used for behavior that is "morally wrong or against acceptable social or professional standards," which seems like a good description of – ahem – a "bad move."
If you want something more slangy, there's the British term not cricket. A UK Slang Dictionary defines the informal phrase as:
Unacceptable or unfair behaviour : I mean, it's just not cricket is it? Knowing that a meal contained beef fat and not telling a vegetarian until after they'd eaten it.
CDO labels not cricket as
humorous, but their example sentence fits very well with the phrase you are asking about:
It's simply not cricket to flirt with another man's wife.
The phrase not cricket isn't widely used in the U.S., but I've known the meaning of the phase for some time now, thanks to a song by the band Squeeze. We'd need a UK native to comment on its currency on the other side of the Atlantic, but at least it would be much more polite than the alternative you are asking about.