Because they had so many knights.
or
Only one, but they get three tech. reports out of it.
or
She wanted to reach the high notes!
or
Drinking, bathing, washing, swimming, etc.
or
got salmonella.
or
They both whine alot!
or
One; after reflecting in the twilight on the merit of the previous bulb.
or
Meet Patty.
or
Climb up a tree and act like a nut
or
Five. One to change the bulb and eleven to say they could do it faster.
or