Best cameo ever? Discuss.
Bob Barker in "Happy Gilmore".
The thread is over, Bitch.
When I was in law school I irresponsibly flew to LA during the semester to go to a Price is Right taping. During filming in the "commercial breaks" Bob took questions from the audience.
One of my proudest moments as a human being was watching him do the Happy Gilmore line live upon request.
EDIT: Along the same lines as YB's: Bob Saget in Half Baked.