Like a catopolt, this is both jolly old fun and sexual.
The male piles "cum" on the end of his penis. He then pulls hard and folds his penis up towards his stomach, almost like folding it in half.
When the female is ready, he lets go of his penis and the cum should fling off the head of the penis and into the air.
The female should be waiting with an open mouth, ready to catch the seman.
Jarred: Lexie finnaly let me try catapenis with her!
When males partake in polygamous anal sex facing in the same direction, i.e. nut to butt, so that the orgy resembles a centipede. Although only a true centipenis can be made with exactly 50 participants, any group of 3 or more is commonly refers to as this for comedic purposes.
"Did you see the MMMM scene in that new pornographic video, 'The Human Centipenis'?"
"Yes sir, I thought Scotty Aces' middle performance was worthy of an AVM."