look up any word, like fleek:
 
2.
To slice the mouth on either side then kneeing the victim in the groin causing the mouth to tear. Popular in British prison.
I'm gonna give that nonce a chelsea smile.
by pippa from home and away April 18, 2003
 
1.
A torturing term used all around the world but originating in Chelsea. The victim's hands are tied or held and the sides of there mouth are cut slightly breaking the strong lip structure. The victim is then kicked very hard in the nuts or in the case of a woman a leg is broken and as the victim screams the cuts rip creating the Chelsea Smile.
That (cunts) been sleeping with my wife, give him a Chelsea Smile.
by James Spencer June 07, 2005
 
3.
Placing a credit card into a persons mouth and then either stabbing them in the stomach or kicking them in the nuts causing them to scream.

Them screaming causes the the credit card to slice the sides of the lips creating a clown smile.
I gave that cunt a fuckin' chelsea smile for fuckin' me wife.
by Bilbin July 13, 2009
 
4.
To place the open mouth of any person, excluding Chelsea Londoners on the kerbing of a road and stamp on the back of the victim's head, causing their cheek skin to tear and bleed. This followed by a kicking to the face and/or chest/stomach.
I'll give that Daz a fuckin 'chelsea smile' outside the chippy after the match.
by Sacha Baron Cohen May 29, 2005