Players are numbered, with the first player being Big Booty. The goal is to sing your way into a rhythm, maintain and increase it, while avoiding mistakes.
Big Booty starts. The player whose turn it is calls out their own number in rhythm, then the number of the player who should go next. Anyone who makes a mistake must go to the end of the line, causing all numbers to shift automatically. A mistake is made when a player falls out of rhythm or simply misses the call of their number.
Here's an example:
Everyone: Big Booty, Big Booty, Big Booty - ooooh yeah
Big Booty: Big Booty → Number 1
Number 1: Number 1 → Big Booty
Big Booty: Big Booty → Number 6
Number 6: Number 6 → Number 7
Number 7: Number 7 → Number 7 (MISTAKE!)
Everyone: Ooh shit !!!
Number 7 must go to the back, everyone shifts up, getting new numbers, and the game continues immediately without pause.
Everyone: Big Booty, Big Booty, Big Booty - ooooh yeah
Big Booty: Big Booty → Number 5
Number 5: Number 5 → Number 2
etc.
Variation: Calling your own number doesn't necessarily have to count as a mistake.