Like, one who insists on being in your lap as you work? Plays with the keys? The (ha ha) mouse?

Remind him or her who’s boss.

Instructions from aBowman’s site, where I found this (via the wide-ranging Froog):

This lively pet hamster will keep you company throughout the day. Watch him run on his wheel, drink water, and eat the food you feed him by clicking your mouse. Click the center of the wheel to make him get back on it.