Gullywhumper 

A very hard rainstorm that brings a lot of rain in a short amount of time. Unlike a hurricane that covers vast amounts of area, a gullywhumper typically refers to a local thunderstorm that turned severe with the rainfall.
Gullywhumpers typically have heavy flooding and standing water in places that normally are dry or drain very quickly after a storm. ie The 100 Year Flood.

That storm last night was a real Gullywhumper. It rained 6 inches in 2 hours! Bullfrog Creek is still flooding over the road.

Gullywhumper by JaxFish September 10, 2018

gullywumper 

A made up fictional monster that Author, Judy Miceli, wrote about in her book "Scaring Bryan!" That would come out at night and attack children who would not listen to their mothers.

Bryan, if you don't go right to bed and do as your told the Gullywumpers will get you tonight.

gullywumper by Steve Rodhouse September 20, 2008

gullywhomper 

A person who is bug eyed and ugly.

Devin: chad is a gullywhomper.

Dustin:I know. Look at them bug eyes.

gullywhomper by Tennesseet Williamst September 21, 2013

Gullywhopper 

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.

Gullywhopper by Rebco April 2, 2006