Background: Coming from the fact that a pig is generally happier in it's own environment - it's own faeces (Makes tastier and tenderer Bacon and Sausages...)
Def: Where one person is extremely happy in the environment they find themselves in
Parachuting into the Playboy hot-tub and finding that their Sun-tan lotion boy is off for the day and they need a new one to oil them up... Expression comes into play when the job is at least 5 mins underway...
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.