look up any word, like bae:
 
1.
A synonym of dip, the clump of smokeless tobacco one inserts into their lip when dipping
That gumper you have looks like a pig pong ball under your lip. That is one fat ass gumper
by Brodybrah January 07, 2010
 
2.
1. Just a total jerk.

2. Someone who just committed a foolish or stupid act and should therefore feel sheepish.

When one feels as though words describing douchebags or fools become boring and trite as they often do, the logical solution is to stay ahead of the curve by employing newly formed words, sometimes out of accident. Hence, "gumper".
1. Dude: I recently read that a 15 year old boy strangled his mother because she found his pot stash and was going to punish him.
Girl: Did she die?!?
Dude: I don't think so. But what a gump. Just a gumper.
Girl: You're a gumper.

2. Waitress: You have a good meal!
Guy Diner 1: You too!
(waitress leaves)
Guy Diner 2: "You too?" Are you kidding me? You're just a gumper, bro. A total gumpz. Watch out for the gump truck.
Guy Diner 1: Aww, come on Jerry, cut it out!
Guy Diner 2: GUMPSTER MCDUMPSTER!
Guy Diner 1: I feel sheepish.
by colgate123456789 March 19, 2009
 
3.
Another word to describe someone who is slow mentally.

Refers to someone with characteristics like the movie character Forrest Gump.
That kid is a true Gumper.
by Alimoons77 May 12, 2014
 
4.
(noun)
Someone who is "Gumpy", lengthy, tall, uncordinated kind of person.
One who's some what like a loser, or a dork.. somebody who falls alot, clumsy, etc.

Dooode, look at that guy over there, he's such a gumper yo'.
Yo' that basketball player sucks, he's a major gumper.
by dEMAR J* February 13, 2009
 
5.
Not the full quid, a few sandwiches short of a picnic..not playing with the full deck.
He's not a full on Mong..just a bit "Forrest Gump"..or a Gumper.
by Ugleebugga September 20, 2010