He’s right — if you accept his premise that calling tea partiers “teabaggers” is meant chiefly as a joke. In that case, yeah, it gets old quickly. But that’s not its main purpose; if it was, you wouldn’t see Obama dropping it into interviews or U.S. senators including it in fundraising e-mails. The point of the term is to deride, not to get a laugh, and the shelf life of derisive terms is a lot, lot longer than the shelf life for cheap gags. “Wingnut” ceased being funny years ago and yet somehow it crawls on, ever ready to signal to listeners that, no siree, its user certainly does not think much of those darned conservatives.