Michael McKean & David Lander (Laverne & Shirley) turned up on Bandstand in 1979 to perform two songs---"King of the Cars" & "Love is a Terrible Thing". Yes, they're sending up the late 50's-early 60's period from which their characters sprang, but it's so much fun. Lander was no stranger to Saturday mornings---he was the voice for Jerry Lewis' animated self in the 1970 series, Will The Real Jerry Lewis Please Sit Down---but if memory serves, McKean would later return with his more famous combo, Spinal Tap, during the 80's.
Lenny & The Squigtones made only one appearance in my home area, and that was for a Cerebral Palsy telethon, where they did "Night After Night". No concert bookings, though, that I know of.