When you pee in a persons belly button, creating a decent sized puddle, then slapping the puddle with your little fella(your dick dip shit). To classify as a true puddle jumper, this action must create a splash, hopefully landing in or around the facial section of the person who was pissed on.
Nick: Dude picture this, last night I pissed on my girls stomach, creating a small pond if you will, on her belly button. Then I slapped it with my mini-wiener creating a small tidal wave that struck her face, it was awesome.
Ron: Oh, you mean you pulled off a puddle jumper? LOL
Nick: Actually I lied, i did that to you last night when you blacked out
and fell asleep on my couch. Hehehe.