"A Glasgow smile (also known as an Anna grin, Chelsea grin or Chelsea smile) is a nickname for the malicious practice of cutting a victim's face from the edges of the mouth to the ears, often using a credit card to hold the mouth open in modern times: the cut - or its scars - form an "extension" of what resembles a smile. Sometimes to further hurt or even kill the victim, he or she would then be stabbed or kicked, most notably in the stomach (or in case of kicking, the groin), so that the face would be ripped apart when the victim screamed. The practice originated in the Scottish city of Glasgow, which gave it its name. It also became popular in Chelsea, London (where it is known as a "Chelsea grin") and other areas of Britain, for gangs hoping to leave a message to rival gang members. If cut deep enough, the victim can likely bleed to death.
Character actor Tommy Flanagan, noted for scars on his face, received the Glasgow smile after being jumped outside a bar at which he worked as a DJ."
That is so... Painful *shudder*