The chimpanzees in the zoos do it,
Some courageous kangaroos do it
Let's do it, let's fall in love. I'm sure giraffes on the sly do it,
Even eagles as they fly do it,
Let's do it, let's fall in love.
"Let's Do It, Let's Fall in Love"; an earlier variant, rather than "Even eagles...": "Heavy hippopotami do it..." - Paris (1928)