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Someone who doesn't have the sense God gave a jackrabbit; possibly a result of inbreeding.
"I can't believe that Tardbilly actually tried to launch a bottle rocket from 'there'!!" Additionally, famous last words are usually "Hey, y'all--watch this!"
by BabyBoyd December 09, 2005
A white dude who thinks he is wanted in a group and really is only let in out of pity.

Or, a retarded hillbilly.
That Emo know-it-all fag boy is a tardbilly.
by QueTacos November 06, 2006
Cross between a retard and a hillbilly
Look at that guy, he is a tardbilly.
by Kevdrea June 29, 2005