Clap your hands but not too loudly

The other day, we were rocking before bedtime and I asked "Evan, did you have a good day today?"

In reply, E starts singing "If you're happy and you know it". I guess, yes, he did have a good day.

After the song, E says "Shhh, pace tuttle seeping, Mommy." So, maybe the song was actually a lullaby for the now-asleep (and imaginary) space shuttle in E's room.