2 years old.
Cow: "Mooooove over"
Sheep: "Naaaaaaa."
or
Two. One to exploit the proletariat, and one to control the means of production!
or
First they have to agree on which is better; the analog bulb or a digital bulb.
or
Can I have your hand, hand, hand, hand, hand, hand, hand, hand in marriage?
or