What should I do if the guy I like won't ask me out?

Ok, so me and this guy I like are really into each other. He shows so much PDA around my friends, and they keep telling me to ask him out. Well he's been back from out of the country for weeks and I had a feeling he was going to ask me out right before he left, but he still hasn't. Should I ask him out or wait for him to ask me? Because I don't want to ask him out and he says no.