Not using double negatives in English is one of those rules that everyone who speaks the language has heard of. While it’s not (yet) destined to the scrapheap of
outdated grammar rules, for many, not using a double negative seems almost as silly as declaring “they” a plural-only pronoun. After all, when you hear someone saying “I ain’t got nothing”, it’s not like you’re going to get confused by what they mean. According to the double negative rule, however, you should immediately question whether the person actually has something and possibly spend hours contemplating the matter.