Nate Robinson invokes the spirit of Karl Malone.
Do you recall when Karl Malone would dunk with one arm flexing as his hand rested behind his head?
Nate Robinson has decided he's going to start that again with his own flair. And that flair is, instead of a dunk, just doing a layup.
I'm not sure I'd advise doing such a celebratory gesture early in the game against the Spurs, though.