What is another word for sucker-punching?
Pronunciation: [sˈʌkəpˈʌnt͡ʃɪŋ] (IPA) 
Sucker-punching is a violent act that involves attacking someone without any warning or provocation. It is a cowardly and sneaky way of attacking someone, and it is considered as an aggressive and unsporting behavior. Fortunately, there are many synonyms used to describe sucker-punching that can be used to express disapproval of such behavior. Some of these words include blind-siding, ambushing, cheap-shotting, sneak attacking, and striking beneath the belt. All these terms portray the idea of attacking someone without giving them any chance to defend themselves or prepare for the attack. Regardless of which term you choose to use, sucker-punching remains an unbecoming and unacceptable behavior.
