The squeaky glitch is a glitch in Super Smash Bros. Brawl that greatly speeds up all the sounds of a character, making them sound extremely high-pitched and "squeaky" until they are KO'd or undergo a mid-match character change. There is currently no known sensible explanation for the glitch.
The glitch results if a Captain Falcon is removed from play in the midst of using his Final Smash, which applies the glitch to the lowest-slot character caught in the move (i.e. player 1). There are two ways to do this:
The glitch may result in the affected character becoming completely silent instead of "squeaky". It is unclear what circumstances cause the difference.