#5. Cypress Hill using the London Symphony Orchestra and Peter Frampton doing what Frampton does um...best at a musical festival.
#4. "Have The Rolling Stones killed." Mr. Burns hears The Ramones and think they're someone else.
#3. Homer crashing U2's concert by saying he's the "potato man."
#2. Mick Jagger, Keith Richards, Brian Setzer, Elvis Costello, Lenny Kravitz and Tom Petty teaching Homer at Rock 'N' Roll Fantasy Camp (already posted this before, but no list dealing with The Simpsons and rock stars would be complete without it)
#1. Not the funniest clip, but it is Bob Dylan on The Simpsons...sort of.