Today marks the 40th anniversary of Sesame Street, a landmark in public television and children's educational programming. Through the years there have been a substantial number of celebrity cameos, many unlikely. Here are some of the best.

It was, and is, the show that taught us all how to count to ten in Spanish, differentiate people in our neighborhood, and tell daily commuters to "screw off," from the trash can we've made into a home.

Did You Know?

The original name of the show was intended to be 123 Avenue B.

[via NY Mag]

Will Arnett Always the magician, Arnett astounds with illusions to impress the kids that arrive at school on the short bus.

REM This song sounds really familiar...

Ricky Gervais Here is the only guy I've seen bring up The Holocaust in front of Elmo.

Richard Pryor This is how cool people learned the alphabet.

Natalie Portman Wasn't this originally a Samuel Beckett play?

R2D2 and C3PO A robot falls in love.

Mel Gibson Watch out Telly, Mel's been drinking. It sounds like an Australian accent, but he's actually just slurring.

Robert DeNiro You'll be swept away by DeNiro's incredible portrayal of a cabbage.