Daniel's first joke

Tonight Daniel made up his very first real joke. It is a take off from this joke -

Knock! Knock!
Who's there?
Interrupting cow
Interrup (MOO!)

that was the original joke. Here's Daniel's ~

Knock! Knock!
Who's there?
Ignoring cow.
Ignoring cow who?
.............................. (silence)

Isn't that great?! We all thought so!!!