Two: One to screw you out of a fee, and the other to send you to a store where they ran out of bulbs weeks ago.
or
Abominable! [A Bomb In a Bull]
or
Only one, but she/he'll have to go out and buy the light bulb adaptor card first, which is extra.
or
The price of bacon would go up.
or
2 years old.
Cow: "Mooooove over"
Sheep: "Naaaaaaa."
or