One that makes my blood run cold is when people put an apostrophe in its when it shouldn't have one - like "I gave the cat IT'S milk". AAAHHH!!! My English teacher actually pronounced "hyperbole" phonetically, like hyper-bowl. Guess that's like the Superbowl only bigger. Also gets me when people say "I won you" when they mean "I beat you" - that's a really annoying one...