Internet based show of action signifying a nod in acknowledgement, to concur, to agree in regards to the actions or statements of an equal peer.
Girl: He cheated on me so I dumped him:
Guy: *ack'nodz*
HaloDude: I say we all go in there and bone rush em with sticky grenades.
Sniper: Yeah then make them chase you and I'll snipe em
Grunt:*ack'nodz*