PART ONE
A: Knock, knock.
B: Who's there?
A: Banana.
B: Banana who?

PART TWO
Repeat "PART ONE" until you feel like a total jerk, then move to "PART THREE".
How many times you repeat "PART ONE" varies from person to person, but I'd recommend at least 3-4 times.
I once repeated "PART ONE" roughly 23 times with a class of high schoolers I taught. Boy, did they hate me afterwards.

PART THREE
A: Knock, knock.
B: Who's there?
A: Orange.
B: Orange who?
A: Orange you glad I didn't say "banana"?

I'm in a band called 999 Megabytes. We still haven't got a gig.