There are a few words that really bother me when misspelled. For example, I cringe when I see 'definatly'. I must have annoyed a few people before I learned that ridiculous is spelled 'ri' not 're'. The whole it's/its, your/you're, and their/they're/there thing makes my skin crawl when I read the wrong one.
What are the misspellings that make you cringe?