Gerard Mulligan as Karl Rove on Letterman 

Gerard was a hilarious master with these bits!😂

I love that the trigger and the pump is both done by his right hand lol

This is stellar

These are the greatest bits ever/

2:15, 3:59 gunnysacking (from wikipedia): to bring something up from the past to maliciously bring the person down during a conversation or argument.

Genius.