Because it was always running out of the pen.
With a cowculator.
In a mooving van!
Get it to do some CARdio
One's a crustacean and the other is a crushed Asian.
Disgruntled
They go on pignics.
Because it came out of the pen.
Because he kept running out of the pen.
Because it had its in-de-pen-dance. I'm posting lots of really bad jokes tonight that just appear in my head, if just one person enjoys just one joke is worth it, good evening.
Because his mother was in the pen, and they didn't know how long the sentence would be.