Bathroom Singing

Why do some people sing in the bathroom? This is something that baffles me.
When I was a kid, I used to hear some of my neighbours sing while having a bath to the tunes of Mario Lanza or Slim Whitman. I thought maybe it was a way to exercise their lungs, or perhaps to distract their mind of the cold water. But now, even with hot water shower, I still hear people sing. My current neighbour sings every time he has a bath and so do all his children. Maybe it runs in the family, I don't know. I still haven't found an answer to my curiousity.