"What are you guy is"? Mail in your apostrophe key.

Possessive, as in "What are the thoughts belonging to 'you guys'" (ok, technically should have been "guys'") It was a typo, not improper grammar thought. (Though I guess it means I should proof read better.)

Part of the problem is that if the "guy's" in your sentence is posessive, there is no plural, and if you say "guys" (without the apostrophe), it's plural but not posessive.

But I'm not exactly an authority on proper grammar. I think I'm rebelling against my mother the magazine editor