Pig wasn't invited to Pink's birthday celebration because they already had the experience of staying with her in Miami and they said duck NO!! She's a dirty, filthy beast. They probably didn't announce they were going until the AirBnB and plane tickets were booked for fear she'd weasel her way into their little getaway. Sorry Piggy, we don't need your midnight munching on snaths and farting all night and blowing up the bathroom five times a day.