"I am about to punch you. Are you ready? It's gonna hurt. Because I'm strong. So I'm gonna punch you. Okay, on 3. No wait, it'll be on Go. Okay. 1....2....3....GO" So, if someone taps your shoulder, you turn and they punch you, have you been sucker punched? After all, you were looking at him/her when the punch was thrown. Fair warning could be as simple as "I'm going to kick your ***". It doesn't take much. Barrett gave no fair warning. You say that like he should have done so. What did you want him to say? "Hey dude, I don't appreciate what you just did so I think I'm going to punch you. Are you okay with that?" Come on, get real.