There's a helpful Seinfeld episode for just about every life situation 
ELAINE: So, I walked up behind him and I tapped him on the shoulder. And I said, "Hi, remember me?" And he furrows his brow as if he's really trying to figure it out. So I said to him, I said, "You little phony. You know exactly who I am."
JERRY: "You little phony"?
ELAINE: I did. I most certainly did. And he said, he goes, "Oh, yeah. You're Jeanette's friend. We did meet once." And I said, "Well, how do you go from that to totally ignoring a person when they walk by?"
JERRY: Amazing.
ELAINE: And he says, he says, "Look, I just didn't want to say hello anymore, alright?" And I said, "Fine. Fine I didn't want to say hello anymore either, but I wanted you to know that I'm aware of it."
JERRY: You are the Queen of Confrontation. You're my new hero. In fact, you've inspired me. I'm gonna call George about something right now.