Someone who is in a fowl mood
Adam lost his poker game so he was a Grumpy Pumpkin
by Miss Jenna December 01, 2005
the person who is the giver of a grumpkin
I'm going to make that bird a grumpy pumpkin by the end of the night
by steesher December 14, 2011
After performing ATM on someone, during which you've pulled out a plum, their teeth become fouled with said plum they become angry and sad and in a horrific grimace have a shocking resemblance to a jack-o-lantern.
My third grumpy pumpkin was with Angela. That bitch was already missing a tooth so it didn't take much to go full pumpkin.
by t-pyle November 08, 2008