English Teachers, Pronouns, and a Joke

I came across an old grammar joke on an English forum I visit regularly (it's listed under "Resources I Use"). A reader asked which is correct: "It is I" or "It is me."

Grammatically, the correct answer is "It is I." Common usage, and therefore the one I use, is "It's me."

Here's the joke:

St. Peter (at the Pearly Gates of Heaven): Who is it?

Voice: It is I!

St. Peter: Go to hell, we already have all the English teachers we need!
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