We can't help but suspect that Robert Pattinson is laughing at some inside joke that we don't get.
Just look at that secretive half-smile. Our 3-month-old nephew does that smile whenever he's getting ready to projectile vomit all over somebody he doesn't like. He thinks it's fun.
So, what might R.Pattz's joke be? We suspect it has something to do with that Aztec floral disco shirt lurking under his suit. Otherwise, we have no explanation for that outfit. At all.