All-purpose insult based on the "out-of-context racial slur" theory.
Combining the words Jew
one may use this to describe someone whose retardedness is far too great to warrant a normal insult.
(Note, the humour of using Jewite is derived from the fact that the recipient of the insult is not of the Jewish faith, the term is in no way meant to be racist. Cos that's just not cool.)