How do you go about propositioning one of my best male friends for casual ?

I know this seems like its coming out of nowhere...but yeah, there's this one guy in particular(whom I happen to be good friends with and also happen to have made out with more than a couple times) and I don't want to date him because he'd make a lousy boyfriend...but I'm wondering how to bring up the prospect of being **** buddies. I probably should just try and take advantage of him next time we're making out on my bed, right?