How to turn him on while making out?

My boyfriend and I makeout often, but we aren't quite ready to have sex, but I wanna spice up making out a little bit!! Any ideas that would really tease him and get him going? Also, people say grab his balls or whatever, but my boyfriend is a drummer and wears the really low skinny jeans and I was wondering can you still do it when he wears those? And how? Thanks for the ideas & advice!!