Nixon: His Inane commentaries like "I guess it means something different to get stoned at Grateful Dead concerts", that and he couldn't like, sound or taste more like a conservative cliche.
Ford: Couldn't fart or Chew Gum at the same Gum. Apparently.
Carter: His hilarious quasi-bitterness after leaving office. Though I guess Camp David runs a close second.
Reagan: The imagery of his speeches and how comical it was, the difference between what he said and what he did. Confirmed Satire's death.
Bush the Elder: Reading "I care" from the teleprompter during a speech to workers groups (? Can't quite fully recall.) Throwing up at the Japanese Prime Minister = Second.
Clinton: He confirmed what we all knew, America is run by Jocks. Cemented his place in the Jockocracy by showing his depth of philosophical thought by wondering what 'sex' meant or even better the word 'is'. A thinker for our time.
Bush the Younger: Marked the Rebirth of Satire, probably too dumb to fart and Chew Gum at the same time though we haven't confirmed it yet. The Fuzzy-Wuzziness Triangulation comfort blanket shielding me from reality speeches were also good. (See Reagan, Ronald)
Probably belonged more in the Youtube clip below than in the Oval Office, it would have alot funnier without the tragic or maddening aspect of it:
http://www.youtube.com/watch?v=TSqkdcT25ss