I'd have to say out side during a thunderstorm..... at night........ considering the atmospher and our temperment...... it was probibly the most exciting sex I've ever had.....
Back when I was involved in church, I was helping out with the youth group and my fiance at the time and I had sex in the church while we were supposed to be watching the youth group durning a "lock-in". not really proud of it (ok I am a little).
I'm surprised noone's quoted that infamous moment on the Newlywed Game when that precise question was answered by a fat Greek woman with "that would be the butt, Bob."