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!"

Jumping On The Bed

Q: How do you stop a black kid from jumping on the bed?
A: Put velcro on the ceiling.
Q: How do you get him down?
A: Blind fold two Mexican kids and tell them he's a pinata.

Knock Knock - Cow

Knock knock.
Who's there?
Cow goes.
Cow goes who?
No, cow goes "Moo!"