He's the angriest Undertale you've ever heard.

Chara: I mean this battle just pukes snot up my ass. It's like you touch the top of the bones you die, you touch the ceiling bones, you die, you touch the floor bones, you die, too far to the right, you die, too far to the left, you die, you die, you die, die, die, die, die, die, die, die, die, die, die, die, die, DIE!