...who is able to talk and doesn't mind living in a box or something. He (or she) may end up appearing in my Revenge of the Walrus game or serving another, unrelated annoying purpose. Go wild.

Ahhh... I can do this. Just let me think. Gimme some time. I'll be back with a character idea.
EDIT: What are you going for? I mean, like, weird, or Mario-like?

What about a jack in the box type character?

Microsoft Office Paperclip

It's for my Revenge of the Walrus fangame, which I've actually been doing some serious work on the past few days. It's a hidden, unlockable character used for making it easier to find hidden goodies in levels.

A jack-in-the-box might work well, especially if it's something a little quirky like a Koopa-in-the-box or something. Although the MS Word paper clip would be annoying enough...