Because he kept running out of the pen.
When he turns his cow to pasture.
I'm on the horns of a dilemma here!
Make him run a lap then do 10 push-ups and sit-ups
They thought the traveling salesman told the farmer to put his name on the dotted swine.
They go on pignics.
A crashing bore.
It's mother was in the pen and it didn't know how long the sentence was.
Stylus.
Because his mother was in the pen, and they didn't know how long the sentence would be.