Cock-a-doodle! Do?

I've often wondered why people say roosters go 'Cock a doodle do!' They don't- they go 'cock a doodle!'- there's no 'do!' at the end.

I may be a city boy, but I've been around enough chickens. (They're so cute and fluffy!)

Cock-a doodle!

David S. Annderson