1. When your penis slips out of its holster, its barn, i.
e, your pants.
2. Also may refer to unnatural through the clothes protruding during
mid hug. Context will be your guide.
Looks like you
got yourself an accidental slippity
doo!
OH MY GOD THAT OLD MAN JUST HAD A SLIPPITY
DOO AND ITS JUST HANGING THERE.