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.