A sucker punch is a blow made without warning, allowing no time for preparation or defense on the part of the recipient. The term is generally reserved for situations where the way in which the blow has been delivered is considered unfair or unethical. In practice this often includes blows delivered from close range or from behind.

In the world of boxing

Boxing

Boxing, also called pugilism, is a combat sport in which two people fight each other using their fists. Boxing is supervised by a referee over a series of between one to three minute intervals called rounds...

 a sucker punch thrown outside of the rules is illegal. For example, when James Butler

James Butler (boxer)

James Butler Jr. is a former American light heavyweight boxer, and former USBA super middleweight champion. He had a career record of 20-5-0, with 12 wins coming by way of knockout, and was nicknamed "The Harlem Hammer".- Biography :Butler started off his career by scoring 18 wins and only 1 loss...

 knocked Richard Grant

Richard Grant (boxer)

Richard "The Alien" Grant is a former light-heavyweight boxer, and former EBA Light Heavyweight and Super Middleweight champion...

 unconscious after losing a fight to him on points, his license was suspended. Because sucker punches come unexpectedly, people at risk of such blows must be alert to the proximity of potential opponents.

Street fighting

The sucker punch is a common street fighting

Street fighting

Street fighting is a colloquial term used to denote unsanctioned, illegal in some countries, hand-to-hand fighting in public places, between individuals or groups of people....

 technique. Experts may feign fear or friendliness to put their opponent off guard or approach him from the side or rear to deliver a surprise

Surprise

Surprise may refer to:* Surprise , a brief emotional state experienced as the result of an unexpected significant event-Places:* Surprise, Arizona* Surprise, Indiana* Surprise, Nebraska* Surprise Station, California or Surprise, California...

 blow. To guard against this, fighters may place their backs against a wall or issue an ultimatum

Ultimatum

An ultimatum is a demand whose fulfillment is requested in a specified period of time and which is backed up by a threat to be followed through in case of noncompliance. An ultimatum is generally the final demand in a series of requests...

against any close approach.

Mainstream media

The sucker punch has been adapted into many films, video games and other forms of media. It can be used to show the antagonist's vileness, the low moral of an anti-hero, betrayal of a someone close to the protagonist, etc, but it also can be used as a weapon of the protagonist to deal against an unfair situation, as the only way to equal the match.