bathroom song
n.— «There are smart and stupid times to visit a public restroom. A stupid time would be at an oldies concert, when someone like Paul McCartney says, “Here’s a song from my new album.” In the concert trade, those are called “bathroom songs.” The lines will be long. Better off holding it in until Hey, Jude.» —“Feet come in handy for flushing toilets” by Ken Hoffman Houston Chronicle (Texas) June 11, 2008. (source: Double-Tongued Dictionary)