Means "You are incompetent or unintelligent." Derives from a bizarre fusion of "you're retarded" and "You're a retard." It's intentionally unclear whether "tarded" is a noun or "a-tarded" is an adjective \.
Man, I can't believe you did that twice in a row. You're a tarded.
by K-Wheezy May 29, 2004
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