I know it means "Buy One, Get One Free." But the literal part of my mind, and that's a big part of my mind I assure you, sees the abbreviation and thinks it should mean "Buy One, Get One." Which you should get when you buy something: that something! "Buy One, Get None" would be a crappy slogan. "Buy One, Get More" would be hard to define (how much more?) and would also be abbreviated BOGM. (Reminds me of that Bloom County strip where Opus panics over how his name can be anagrammed as "soup," and then really panics over how his mom Bougm has a name that can be anagrammed as "gumbo.")
Literal Me wants it to be BOGOF. But I also admit that "BOGOF" sounds like a squat, hairy bug.