I don't think it's stupid. Think of what a cool garden or door stopper those things would make. We have lots of rocks....maybe I'll paint something out of one of them.......... or just throw one at you. :P
There is a rather normal looking rock in my backyard with a Koala bear painted on it. 6th grade art class, back then I probably wouldn't have thought about painting the the rock into a representation of some other object.