Permanent grin. Usually a result of great fortune arriving in someone's life; a brand new love, winning the lottery (or one of my personal fav's: watching someone illegally passing on the shoulder during rush hour and promptly getting NAILED by the cops.)
source: R.Lutz of Montana
Look at the perm-a-grin on Rob's face. He is totally twitterpated with Kristy. He smiles all the time; can't stop talking about her; he is always texting or calling her. That boy is whipped!