uh....pretty sure that a Punch is done with a FIST....a Slap is an OPEN HAND!
I just can’t damn believe this. Okay, he gave him a sucker slap. The emphasis is on “sucker” not the method of delivery.
from Wikipedia:
A sucker punch (American English), also known as a dog shot, coward punch, king hit or one-punch attack (Australian and New Zealand English) or cold-cock (American English), is a punch made without warning or while the recipient is distracted, allowing no time for preparation or defense on the part of the recipient. The term is generally used in situations where the way in which the punch has been delivered is considered unfair or unethical, and is done using deception or distraction, hence the term ‘sucker’ used to refer to the victim.
Notice the reason the term “sucker” is used.