What are some red flags to a guy wanting to be social with you?

[Anonymous]

Say you're at a social place or a bar or university or even at a grocery store or otherwise and there's a young slim average looking guy wanting social with you, what are red flags that you don't want guys to do when they want to be social with you?

[Bubbles45]

It's fine if guys wanna be social, don't don't be overly sexual and stuff like that. That's my only real requirement.