When someone you don't like or don't want to talk to right now, says hi, walks by, or is in a crowd jumping to see over people's heads just to get you to notice them and all you can do is nod while looking at them.
"That creepy guy from work who's obsessed with me kept calling my name out really loud in the lobby while I was talking to my crush"
"What did you say?"
"Nothing, just gave him the nod of aknowledgement"
a nod of the head (either a swift upward jerk of the head, or a slower, downward nod of the head) sometimes exchanged between African-Americans (particularly males, regardless of age), given in acknowledgement of each other's presence and the presumed, shared struggles of being an African-American man. Prevalance of the nod varies greatly from city to city or geographic region.
Non African-American companion upon observing the Nod: "Do you know that guy? Why did you two just do that?"
African-American man: "No, I've never seen him before. I was just giving him a 'Nod of aknowledgement'. We don't all know each other; it's just a form of respect."