How to start a conversation on limits?

Taylor

I have been sleeping with a guy off and on for almost four years now, and we are starting to see each other more often and more hook ups of course. I really enjoy sex with him because hes the most comfortable I've ever felt with anyone, but how do I tell him I'm ready for him to be a little more rough, maybe a little experimental, where would he draw a line in the sand with out me freaking him out??