The sensation some males experience when farting while seated. When the gas has nowhere to escape, it often gives the feeling of a bubble swelling around the scrotum, or nutsack.
"After eating that burrito and having to sit in my car for an hour, I had mad nutgas."
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.