This particular homophone issue has been handled previously in fandom_grammar by melayneseahawk in another Friday Funny and chiroho in a Blast From the Past about a year ago, as well as green_grrl's article from 2008.
I do want to point out that there are some countries where the use of "Nazi" would not be prudent, so usually said person would be called a "Grammar Fiend" or some other variation on that.
I don't know about any other grammarians, but this one is tied with your/you're and to/two/too for a grammar-related issue that can set my blood to boiling instantly when I see it. It's also one of my big reasons to advocate for a beta, because spellcheck doesn't always catch these issues. And don't get me started on that period that should actually be a comma, or the missing period at the end of the phrase.
So what do you do to make sure you don't confuse these homophones?