In "The Californians," when Bill couldn't keep a straight face even if his life depended on it.
In this sketch that was cut for time, "Renaldo and Alexi," where Bill couldn't even read the cue cards because he was laughing too hard.
In "The Californians," when Bill made himself chuckle and then just couldn't stop laughing off-screen.
And finally, in "Weekend Update," when New York's hottest club took a VERY dark and unexpected turn.
Honestly, I think we can all agree when I say, Bill, please NEVER stop breaking character.