How should I ask bi friend if he wants to experiment

I'm in college right now, just getting out of a relationship with a girl. I've known my friend since highschool and we have a great time hanging out and we have a lot in common. We've grown apart a bit since highschool but still close. He's told me before he's bi (and he knows im bi im pretty sure). He's really cute and i think something might be there.

The two of us were at my summer cabin drinking one time when he randomly took off his shirt? Does that mean something? How do I go about asking if he wants to try stuff w/o making it weird or ruining the friendship? He's too timid to bring it up so I think i gotta be the one to do it.