Okay, real quick like: The stickers you refer to are cut from vinyl stock, using a computer-driven plotter with a small knife. Sign shops, among others, use this sort of device to make easy, quick, stick-on lettering for various signs.
Scan a pic of something, make a few adjustments in a graphics program, import it to the plotter software, insert the roll of whatever flavor vinyl or plastic sticker stock you want, press “go”.
You can walk in with a rough pencil drawing, and walk out in less than an hour with the completed sticker. Size is limited only by your wallet and the physical dimensions of the raw stock.
Years ago, somebody somewhere wanted to publicly display his derision at some item or device or other, and had one of these shops (there’s literally a million places that can do this nationwide) and so either he or the sign shop ginned up a low-res pic of Calvin urinating on that particular object.
I’m fairly certain the first few were of the ubiquitous “Ford Vs. Chevy” argument- the stocker on the Ford depicted Calvin urinating on a Chevy logo, and vice-versa.
This eventually broadened into including Dodge, Jeep and various foreign car makes, then pictures of Saddam Hussein or Bill Clinton, then short messages like “Mean People” or even “Prop. 24”.
Eventually it transmuted into a Calvinlike girl figure squatting over the same logos, got sidetracked into showing the kid with a squirgun rather than urinating, and corrupted into the aformentioned religious iconography.
As for suing, it’s more decentralized than KaZaa- Watterson would have to attempt to sue individual sign shops for one or two supposed copyright violations, and he’d have to prove the image was his and wrongfully used. The time he could have done even that is long past- the stickers predate the cancellation of C&H.
Personally, they’ve been done to death. The kid’s pissed on anything and everything, they can be found on every sort of vehicle from ricers to 4X4s to BMWs, and they’re all the frikkin’ same!
Show some imagination, people! ('Course, about the only thing left for him to piss on is himself. Be kind of an interesting yin-yang thing- Calvin pissing on a “Calvin Pissing” sticker, which is pissing on the kid pissing on the sticker, which is…)