I probably shouldn't, but I'm going to...
there is a way to orgasm doing iron cross chin-ups because of the way our lower abs / hip flexors interact with he soft tissues down there
( that's the one where you raise your legs up to the bar )
those:
http://en.wikipedia.org/wiki/Hip_flexors
I did it entirely by accident once, and then deliberately ... enough times

the only problem is it tends to clench up your muscles, and is probably not good for you at all
Disclaimer:
I take absolutely no responsibility for people falling off chin-up bars.
also, here's a woman that did it too:
http://tnation.t-nation.com/free_online_forum/sports_women_training_performance_sorority/roman_chair_orgasm
so, people have been doing this a while lol!