Although middle school students are unpredictable, I was still surprised during seventh grade Speech/Drama class when a student suddenly burst into a verse of "A Penny For Your Thoughts" by Tavares. It was a decently sung version, too, with a better grasp of the high notes than most people have.
I still wonder what prompted that in the middle of class. He didn't sing it to anyone in particular but apparently felt inspired to suddenly entertain the class with a hammy but generally on-pitch rendition.
The spirit sometimes moves us to act in odd, unexpected ways, I suppose.