Why are there barely any funny knock knock jokes that don't involve physical contact?

Question

Here's the funniest I've heard:

Knock knock

Who's there?

Kevin Federline

Kevin Federline who?

Exactly!

Any more funny ones?

Answer 1

lol that's a good one!! No, sorry, I don't know of any off the top of my head.

Answer 2

here is an old one for you---knock, knock---whos there--boo--boo who---sorry i did not mean to make you cry

Answer 3

my answer it's awesome dude........., one star for your jokes