I can't do it...I've had numerous invites over the years and it's just too awkward for me to consider. I've done several ffm and mmf's but when I do a mmf I have to be 1st one in...that's my deal. Idea of following a train of guys freaks me out healthwise and egowise. And I tend to feel bad for the woman in that scenario, just seems pretty brutal and not very respectful, and I realize that's only my perception. But ideally I'm the only swinging dick in a room, but that's just me.
I'd totally do an orgy though, that could be fun.