Belly flop.
4 seconds sound clip from the Cloudy with a Chance of Meatballs movie soundboard.
You can hear this line at 00:36:21 in the Blu-ray version of the movie.
Quote context
[...]
- Come on, Sam, what are you waiting for?
- Nothing!
- Whoo! Yeah. Hee-hee. Boing, boing, boing, whoo! Whoo!
[...]