How many Zen Buddhists does it take to screw in a lightbulb?

Four: One to screw in the bulb;

One to not screw in the bulb;

One to both screw in the bulb and not screw in the bulb.

And one to neither screw in the bulb, nor not screw in the bulb.

Is funny because Buddhism aims at enlightenment — something that occurs by the simultaneous destruction and non-destruction of the darkness. Ah you got it: I hear one hand clapping.