It's a Choir thing.

A list of things only choir people seem to find entertaining:

Playing with large chimes that play incredibly low notes.
Playing with small chimes that sound like pounding metal, striking it again and again.
Playing with chimes, picking dissonant chords and playing them all at once, again and again.
Singing off key while someone is singing beautifully.
Everyone singing in a different key, namely R flat Major.