Charley Gallay / Getty Images
Funniest: Ryan Seacrest in 'Knocked Up'
Ryan Seacrests brief appearance in Knocked Up had all the elements of a great cameo:
1. It was unexpected (Hes not a member of the Apatow clan).
2. It wasnt a stretch (whats more natural than Seacrest preparing for an interview on "E!"?).
3. It was hilarious (he had the fake nervous breakdown that we all assume he must have, but we never see because no one works harder than Seacrest). In other words, Seacrest up! Knocked Up.