What's with my cat?

He's five years old and just started chewing on everything in my room recently.  Right now he's mauling my sock like it's a fresh piece of meat.  Is he teething or something?

Sock rape is the feline equivalent to masturbation.  Since they can't auto-fellate as well as dogs can, they have to resort to forcing themselves on innocent socks instead.

Your poor kitty just needs to get laid.