When a poop log rears it's brown head out for a peek, only to retreat to it's rightful home at the moment, the ass.
Man! I almost messed my trousers, thankfully it was only a frightened turtle, so no soilage! *high five*
When you're so cold, that your penis tries to suck back into your body like a frightened turtle into it's shell.
"Dude, you should know better than to go skinny-dipping on the first date. You never show the frightened turtle to a chick who hasn't already seen your meat."