A lie; something that is utterly made up and/or false.
Rebecca: Jordan is a gullywhopperor!
Erin: What gullywhopper did he tell you this time?
Rebecca: He tried to tell me that Kyle's trout is 12 inches long.
Erin: He should really stop gullywhoppering to you...it's just not funny anymore. I mean we all know that it's only 11 inches.
by Rebco March 15, 2006
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