What to Wear:I mean, the hardest thing about this one is going to be the mask. You might have to go to a lot of Halloween stores to find something that matches. You can always find something close, then add details (like paint in the blue eyeshadow, spray the hair green, you get the picture). Pair with a big Elizabethan collar and a red jacket.
How to Act: Well, the first time we see this guy, he's having sex with another clown. So, there's that. Otherwise, just be generally creepy and stalk everyone around you.