This is literally exactly the same as casting a curse. The three fold law is Wiccan dogma not a law of physics, so there is not bad karma for cursing. This is not even how karma works. Stop being holier then thou!
The ketchup prank. Baking soda in ketchup bottle, when shook it will explode. This website has tons of great pranks :)<--- at this point, I think we should engage in a prank war with the other science advisories