I just finished watching a relatively recent interview with Christopher Guest, Michael McKean, and Harry Shearer (of Spinal Tap fame). It looks like some sort of "local" TV program, called "The Q & A Cafe With Carol Joynt". The host is interviewing the guys about their current projects.
At about the 40-minute mark, somebody's cell phone starts ringing, and Christopher Guest quips, "I guess that means there's a commercial?"
Carol Joynt, the host, replies, "It means somebody's going to get spanked after the taping!"
Link to the relevant bit:
https://www.youtube.com/watch?v=R43Wu77SzOY#t=2413