burst out singing

To begin singing, often suddenly or unexpectedly. I went to a school for the performing arts, so it was not unusual for people to burst out singing in the hallways between classes. A: "At that restaurant, they sing opera songs throughout the evening." B: "Seriously? Like, my waiter will just periodically burst out singing?" A: "Yes!" I'm trying to forget that it's my birthday, so please don't have everyone burst out singing, OK?