A play on words of 'Curious George' which is a person that ruins an intended joke or light hearted comment by being too serious.
Joker: "Ha ha, when that kid rides by on his bike, you should throw a stick in his spokes."
Buddy: "That's not very cool, they could get hurt."
Joker: "...way to kill the mood, Serious George."
Buddy: "That's not very cool, they could get hurt."
Joker: "...way to kill the mood, Serious George."
by Bearded Fist September 21, 2013