They can make little things count.
or
Because they only know their ABCs "Anybody But Clinton".
or
they always take things literally.
or
A jump rope.
or
Clerk: "Yes, sir. What size does your alligator wear?"
or
Two. One to screw it in, and one to stab the other in the back and take all the credit.
or
1,000,001: One to change the bulb and 1,000,000 to rebuild civilization to the point where they need light bulbs again.
or