My roommate in the army and I were discussing weird sexual acts with a Brit officer, and he told us about 'frogging.' It's where you nail a girl in the ass from behind. Shove two fingers in her nostrils to yank her head back, and use the other hand to punch her in the kidneys every 3 - 4 strokes. Supposedly it makes her sphincter tighten up. I'm not sure what effect yanking her head back has, other than making it rough and uncomfortable for her, and I'm not sure what it has to do with frogs, but it's hilarious.