I was debating a progressive, and he got me with a left hook "oh, you watch Glenn Beck, this conversation ends now because he is a racist/idiot etc" even though I was not using Glenn Beck as a source for any argument even though he was using a Village Voice article that was horribly written hack/yellow journalism ... So if some one says "oh you watch blank blank, you're wrong"
I know its a fallacy-I just cant remember which one. ... appeal to authority maybe?