Typically known as a line used before The Joker slashes a victims face to make it look like they are smiling but has also come to be known as a common day phrase said to one who's got a stick up their arse.
It should be noted that this disfigurement is a common day occurance in Glasgow, Scotland. Can be seen on actor Tommy Flanagan though there are far worse examples. Known as a Glaswegian smile
Friend: Mate, you have no idea what you're on about, Sara is way hotter than Nicole.
You: I respectfully disagree.
Friend: Fuck you mate, you deserve an asswhooping for that opinion, fuck off I can't even look at you.
You:y so srs?