Two. One to take out the bulb and drop it, and the other to try and sell it before it crashes.
or
Time is fun when you're having flies
or
One has claws at the end of its paws and one has a pause at the end of its clause
or
Two, one to call Daddy, and one to get the (pick one:) mineral water/Tab.
or
Twenty. One to hold the bulb, two to turn the ladder, and 17 to be on the guest list.
or