Dangerously Bad Grammar

I've touched on some quick tips like these: If you can use "farther," don't use "further"; if you can use "whether," don't use "if"; and if you can use "and," don't use "or." An excellent example of the last of these can be seen on some gas pumps: "Turn off cell phones or other electrical devices to avoid possible explosion." A logical, though not common-sense, response might be, "I think I'll choose to turn off my laptop." Clearly the instruction is to turn off all electrical devices and should read, "Turn off cell phones and other electrical devices."