A term of mild abuse for a person who is intelligent, but then does completely retarded things in social situations.
When I went to introduce my friend to him, she said "It's nice to meet you!", and fuck-snausage said "yeah yeah, whatever" and walked straight passed her.
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.