Johnny Cash on Sesame Street

Set your time machine to -40 years and enjoy some classic clips of Johnny Cash on Sesame Street!
Five Feet High
Biff helps with a visual explanation of height.
Nasty Dan
Oscar the Grouch seems to like this Nasty Dan character just fine.
Ghost Riders in the Sky
Okay, this is The Muppet Show, not Sesame Street, but it's pretty great.