"Have you seen the little piggies?" joke

(My friend Brad in NYC told me this one yesterday.)
There was once a man from the city who was visiting a small farm,
and during this visit he saw a farmer feeding pigs in a most
extraordinary manner. The farmer would lift a pig up to a nearby
apple tree, and the pig would eat the apples off the tree
directly. The farmer would move the pig from one apple to
another until the pig was satisfied, then he would start again
with another pig.
The city man watched this activity for some time with great
astonishment. Finally he could not resist saying to the farmer,
"This is the most inefficient method of feeding pigs that I can
imagine. Just think of the time that would be saved if you
simply shook the apples off the tree and let the pigs eat them
from the ground!"
The farmer looked puzzled and replied, "What's time to a pig?"