The heinous act of cutting a victim's face open from the edges of the mouth to the ears originated in Glasgow, Scotland, hence its nickname "The Glasgow Smile." Also known as The Chelsea Grin and The Anna Grin, the victim would often be beaten or stabbed after the incisions were made, thus ensuring that the wounds would rip open as the victim screamed, leaving a smile shaped scar...if the victim didn't bleed to death, of course.
Real life instances of the Glasgow Smile's infliction include:
Character actor Tommy Flanagan (Braveheart, Gladiator - top image), who received his scars outside of a Glasgow nightclub late one night in a mugging that left him close to death.
Elizabeth Short, better known as The Black Dahlia, was given a Glasgow Smile as well.
Famous fictional depictions of The Glasgow Smile include:
The 2001 film Ichi The Killer featured a character named Kakihara (second pic), who proudly sports a Glasgow Smile held shut with piercings.
The 1992 film City Of Joy depicted a young girl's face being carved in such a manner, as punishment for turning on a slumlord.
The 1928 silent film The Man Who Laughs, based on the 1869 novel of the same name by Victor Hugo, features a protagonist named Gwnplaine, whose face was carved into a Glasgow Smile as a child, leaving him with a permanent toothy grin.
And need I mention Batman's arch nemesis, The Joker?
I didn't think so.