My Algebra II teacher used Row, Row, Row Your Boat. She also wore a t-shirt with the quadratic equation on it, under her sweater. As she finished the song, she pulled off the sweater, much to the surprise of the students (the shirt stayed on, so things were still safe for school).

I'm still not sure if it was the song or the shock of seeing your teacher pull her clothes off. While I can still remember the song by heart, I also shudder every time I sing it.