Knock Knock - Remember

Bob: "Will you remember me tomorrow?" 
Bill: "Yes"
Bob "Will you remember me next week?" 
Bill  "Yes"
Bob: "Will you remember me next month??"
Bill: "Yes"
Bob: "Will you remember me next year?"
Bill: "Yeah"
Bob: "Knock Knock"
Bill: "Who's There?"
Bob: "See, you forgot me already!"

Owl Talk

Q: What's the difference between a white owl and a black owl?
A: A white owl goes WHO WHO WHO A black owl goes WHODAT WHODAT WHODAT

Knock Knock - Ketchup

Knock Knock
Who's there?
Ketchup
Ketchup who?
Catch up with me and I'll tell you!