An avoidance nod is an action when trying to avoid someone.
This technique is usually used when someone you know wants to talk to you, or tries to say hi. The avoidance nod is a simple little nod in there direction, which is usually followed by walking away from that person.
Scarlet: Hello, steve!
Steve: -Nods and walks away-
Jason: Did you just use the avoidance nod on her?