"'But I do have one federal election law joke if you'd like to hear it,' Colbert said.
'Knock knock?' Colbert said.
'Who's there?' asked the crowd.
'Unlimited union and corporate campaign contributions,' Colbert said.
'Unlimited union and corporate campaign contributions who?' the crowd replied, not quite in unison.
'That's the thing, I don't think I should have to tell you,' Colbert replied."