When it's going cheep!
Did you hear the one about the crow and the telephone pole?
He wanted to make a long distance caw.
or
Because it might crack up!
or
Two. One to assure the everything possible is being done while the other screws the bulb into the water faucet.
or
When a rooster wakes up in the morning, its primal urge is to cluck defiance.
or