seriously, one of my ex's used to make a very very serious face while in the act, try pushing your lower jaw out as far as it'll go and only baring your lower teeth...that was it, always cracked me up so much.
Another time we were in someones spare bedroom, and were woken by the couple in the other bedroom going hammer and tongs, we giggled all the way, the walls were paper thin, so we heard everything, like
'You like a bit of that don't yaaaaaa' <SLAP>,
and other choice phrases, we were both clamped on a pillow trying not to laugh out loud, we failed and all the noises stopped.

We laughed for about 10 minutes straight, really side splitting stuff, the type you can't get your breath back....
Crazee KidWhat this requires is a subtle mix of psychology and extreme violence...
IDGAS#25
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?

The Wobbler Returns