A grumplebump is a person who is acting grumpy out of character. They are regularly very good natured but are now acting grumpy without apparent reason.
:Hey did you talk to that nice girl Bonnie today?
:Yah I did but she was acting like a douche and being a total grumplebump.
:Yah I did but she was acting like a douche and being a total grumplebump.
by Chody Dootch October 11, 2011