The definition in Merriam Webster for "sucker punch" is:
to punch (a person) suddenly without warning and often without apparent
I would play for a while a game named Mafia Wars on Facebook long time ago.
One of the things we can do as gangsters is to sucker punch someone.
I remember a group named "Sucker Punch" that was once opened to punish gamers
who bully other players. I really don't understand what bullying means.
Gamers are supposed to bully each other for money and other achievements.
Now, I use the "pidgin" to Skype. Someone just sends me more and more
friend requests. I know nothing about that individual, so I asked that
individual why he or she keeps sending me those requests. I'm waiting for
his or her reply. If he or she keeps bothering me, maybe I will add them to
a sucker punch list, and ask other Skype users to lend a helping hand.