We've heard Dweezil do it .. This is the Master in 1974 ... sure I was there .. Kind of long ... if too much jump ahead to 5:30 ..., This is Live in Boston ..
Frank Zappa - Echidna's Arf & Don't You Ever Wash That Thing? - 1974, Boston (audio) - YouTube (http://www.youtube.com/watch?v=I0C0L_g4Wjg)

fantastic musicians. Watch Ruth. Thanks