a whole nother
I absolutely detest when people say "that's a whole nother story" Please understand, you cannot shove the word whole into the word another to make your point. Well, you can, but you sound like an idiot.

While I'm at it, I should also mention that I hate when people use plural forms of pronouns when speaking of a singular, for example, "when dropping of your child, please leave their backpack on the hooks in the hall" Grr.