From Zappa Wiki Jawaka
The Turtles were an American rock group, best known for the hits "Happy Together" (1967) and "Elenore" (1968).
In 1970 the group's lead singers Mark Volman and Howard Kaylan joined Zappa's band for four years. Their performance of Happy Together is the punch line to the sketch Do You Like My New Car? on Fillmore East, June 1971.