I saw a bumper sticker once that cracked me up. It read,
From the early Church on, the second coming has been imminently expected - and even falsely predicted - so many, many times. But however long our Lord tarries, we are expected to live as though He might return tomorrow morning, and that's the really important point.
That one always gives me the giggles too.
Here's one I saw, on an American Indian's truck once, had me awed by the honesty:
"Trust the Federal Government? Sure! Ask any Indian!"