Interesting.
I spoke yesterday to a friend who had upon occasion dabbled with the hole where his wife can't get pregnant. He described to me a recent incident which was spontaneous and involved alcohol.
Forgive me for this next part and the lack of elegance, but... he got poop on his dick, he was grossed out and has thus sworn off use of the backdoor.
The best part about the conversation was that his wife was sitting with him and attempting to defend herself throughout his description of the events which took place, blaming him for it being his idea and not giving her time to... uhm... release, beforehand. It was quite entertaining.