I'd imagine pein, pain and French peine are related. The French means punishment or sentence, sorrow/grief or pain/trouble.
The English and French are derived from Latin poena meaning penalty/punishment/pain. I assume the German as well, although I think there's less Latin in German.
Anyway back to pants, Calvin definitely looks better in his. Tom's conversation is probably slightly more interesting, but unfortunately that doesn't outweigh the starfucking Eau de desperation.