Oxymoron, eh?
Another interesting term is pleonasm, the use of more words or word-parts than is necessary for clear expression... or being redundant if you will.
Some prime examples are:
dumbass DakotaT
redneck Packers fan
blissfully-ignorant Zero2Cool
idiotic cheesehead
inbred Packers fan
numbnuts DakotaT......oops, being redundant again.