When a person correcting someone else's grammar, spelling, or general intelligence makes a grammar or spelling mistake themselves. This does not count if the person has intentionally made the mistake. The phrase comes from "dramatic irony", but is not actually a form of irony.
On an Internet forum:
> > These stupid people are just crybabies who complain when they don't get they're way!

> Your an idiot because you can't spell!

Oh, the grammatic irony....
by illuminatedwax April 18, 2007
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