Green’s Dictionary of Slang

(mainly teen) used to indicate one’s complete contempt for the subject of the excl.; usu. as snubs to him/her.

1934		Neuphilologische Mitteilungen XXXV 130: Prep-school slang [...] snubs interj. accompanied by making a long nose [OED].
1945		E. Waugh Brideshead Revisited 135: Now I shall tell her I have had it straight from a real artist, and snubs to her.