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someone who looks or acts retarded, derives from jummy
"that kid is a jum jum"
by shamone21 March 07, 2008
Jumjum is short-hand for food envy. It can also be used to berate someone who is taking too long to eat and talking too much.
"Steve got chips, iv got serious Jumjums"

"quit yo' jumjum jibber jabber and eat your food"
by greeneyed monster January 27, 2010
butt scrog
dude use this cloth to clean the jumjum up
by jizzmasterZero June 04, 2004