My own "Crazy Shit" that happened during a GURPS game my brother ran:
Our group was heading down on spiral steps cut into the wall of a well, and we were confronted by a floating monster that came up the middle. My warrior type character tried to attack and rolled a critical failure. The result was he accidentally skewered the healer behind him on the stairs with maximum damage. The nearly dead healer had a critical failure of her own, and managed to kill herself instead of saving herself. Everyone else was focused on the threat, so no one else saw the 2nd failure.
Afterwards when anyone was injured they would yell at me for murdering the healer. Yea double botch!