Mixed songs

Have you ever noticed how the "Alphabet Song" has the same tune as "Twinkle Twinkle Little Star"?

This is providing me with an endless source of entertainment. When one of the kids starts singing "Twinkle, twinkle little star", I chime in with "H I J K L M N O P". And of course, if they start with "A B C D E F G", I add "How I wonder what you are".

Endless amusement for me, endless frustration for the kids. I'm cruel, I know... ;)