We have a lot of bullet holes in our highway signs, but I've never seen anybody put stickers on them. I can honestly say I've thrown a lot of empty beer bottles at highway signs out of a moving car, but I've never shot at one, not even out in the middle of nowhere.
We used to have contests back in high school to see who could steal the most signs in one night. We had some kind of "point system" based on the height and size of the sign as well as surrounding lighting, traffic flow, etc.
Sometimes it wasn't feasible to actually shimmy up to remove the sign.
I distinctly remember a green 1970 Chevrolet Caprice rolling slowly through town in triumph, about 6 feet of a steel sign post and a 2-foot mass of dirt, weeds and concrete protruding out the driver's side rear door window. Apparently it was easier to just rip the whole thing out of the ground sign, post, concrete and all.