Pertaining to, speaking of, or just downright calling someone retarded or a retard. Originating and somehow managing not to venture outside of the boundaries of the Athens-Clarke County Public School System in Athens, GA, lump lump has been used for generations of students when describing special needs kids, short buses, and teachers who can't teach for shit.

a large vehicle, usually in the form of a bus or large van, filled with people with little brains, little age, or little drivers license and car.

A replacement of the "F" words F*** and F***ing. Made popular by Princess Lumpy from Adventure Time on CartoonNetwork.

When a group of friends have an inside joke, and another person is asking what's so funny. Definition comes from the movie 'Menace to Society'.

Caine: You don't wanna go out like Willy Lump Lump.
Sharif: Who is Willy Lump Lump anyway?
Caine: Ah man, don't worry about it, it's an inside thing.

A male with a sexual disease.

someone who believes anything

This is a man who says "Oh my god" and "You're kiddin' me" a lot. He dances like Carlton, mostly to the song "Apache" by Sugar Hill Gang. He eats excessive amounts of White Castles and irons his underwear and socks every day.