Taken off the New Zealand slang word "egg", an Eggwin can refer to someone who is being an annoying idiot,
it can also mean someone who is very smart and annoying by using his/her/their intelligence against people with lower Intelligence.
Example 1
Person 1: Bro stop your being such an eggwin
Person 2: Nah bro you're just dumb
Example 2
Person 1: Bro stop being dumb you absolute eggwin
Person 2: Drrrrrrrr