Restaurant. I always want to spell it restaraunt and have to physically restrain myself. Or use an eraser.
Refrigerator. We've had this conversation before. I always want to spell it refridgerator. But did you know the dictionary lists the abbreviation for refrigerator as fridge? Where that "d" came from I have no idea. My mom always spells it "frige" and I always say it looks weird. She always says, "Refrigerator doesn't have a 'd.'" But fridge does, Mom, so there. And yes, I am aware it makes no sense whatsoever. But hey, that's English for ya.
Definitely. I can spell it now, but I used to always write definately. One day I realized it's like the word "definite" and I haven't spelled it wrong since. Maybe it shouldn't be on this list. Or maybe I should change the title of this post to "words I never have and hardly ever do spell correctly." No, that sounds stupid. I'm leaving it like it is and you'll just have to deal with it.
Surprise. No one says sur-prise. We say su-prise. And that's how I always try to spell it.
Separate. Sep-er-ate. I'm a huge fan of spelling by pronunciation.