An evil, sinister object. Reports vary on what the catbrush can actually do, but one thing is clear: Use the catbrush once and it's all over. Stay away from the catbrush. Don't listen to Garfield as he shrugs it off and compares the catbrush to a measly toothbrush.
Jon: OH NO!
I'M USING THE CATBRUSH!!
Garfield: Gee, I don't yell when I use his toothbrush!