Flirting

Why did he say "Don't tempt me"?

So there's this guy that I have a crush on. We both go to the same college and major in the same field of study and work together. One of our professors was teasing me that I like him (the guy that I like actually said something to make him start teasing me... I can tell that the guy I like likes it when the professor teases me). I just played it off, trying not to seem too obvious. Afterwards, the guy I like and I were working in a room by ourselves. We were play arguing when he said in the middle of our play arguing "don't tempt me" and I asked him "tempt you to do what?" and he said "something I might regret." He didn't sound upset because he said this while we were flirting/play fighting. It's not that I can't imagine what he could have meant by this (I can) but I'd like to know your thoughts on what you think he could have meant. What do you think he was tempted to do or not do?
Why did he say "Don't tempt me"?
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