Two. One to take out the bulb and drop it, and the other to try and sell it before it crashes.
or
Two. One to exploit the proletariat, and one to control the means of production!
or
It takes two to tangle!
or
100: One to do it and ninety-nine to say "I could've done that."
or
I said, "I've been on telly but I'm no Dean Martin".
or