Knock Knock / Who’s there? / Little old lady

Knock Knock
Who’s there?
Little old lady
Little old lady who?
Wow I didn’t know you could yodel.

This is another knock-knock joke. In this one, the jokester is intentionally misunderstanding the listener's response as an attempt to yodel. The humor lies in the fact that the listener wasn't attempting to yodel.

My dad used to tell this periodically, so I guess it is also a dad joke.