Two — one to change the bulb, and one to write a song about how good the old light bulb was.
or
Three skunks fighting over a pickle
First dog: My master calls me Furball. How about you?
Second Dog: My master calls me Sitboy
or
Because it would fall over if it lifted the other one.
or
Can I have your hand, hand, hand, hand, hand, hand, hand, hand in marriage?
or