Loose/lose drives me insane.
Just as bad is "would of," "could of," "should of," etc.
And while I'm on the subject, "and etc." may someday make me snap. On a related note, "With au jus" was going to cause me to be violent at one point, and then someone told me to think of it as a regionalism.
The "think of it as a regionalism" idea may save me from having a stroke. I live in Ohio, and the gratuitous preposition at the end of a phrase is ubiquitous--i.e., "Where's the party at?" I've succumbed to it myself, I'm afraid.
In fact, I'm getting worse all the time. I'd better stop complaining, because if I searched my own posts I'd be appalled.