One of the most popular songs among children. See the lyrics.

If you're happy and you know it, clap your hands
If you're happy and you know it, clap your hands
If you're happy and you know it, and you really want to show it
If you're happy and you know it, clap your hands.

If you're happy and you know it, stomp your feet
If you're happy and you know it, stomp your feet
If you're happy and you know it, and you really want to show it
If you're happy and you know it, stomp your feet.

If you're happy and you know it, nod your head
If you're happy and you know it, nod your head
If you're happy and you know it, and you really want to show it
If you're happy and you know it, nod your head

If you're happy and you know it, turn around
If you're happy and you know it, turn around
If you're happy and you know it, and you really want to show it
If you're happy and you know it, turn around

If you're happy and you know it, say "we are"
If you're happy and you know it, say "we are"
If you're happy and you know it, and you really want to show it
If you're happy and you know it, say "we are"