Synonyms for Stag (same or very similar meaning)
WordNet sense 1 (male red deer):
hartWordNet sense 2 (give away information about somebody):
betray, denounce, grass, rat, shit, shop, snitch, give away, tell onWordNet sense 3 (watch, observe, or inquire secretly):
sleuth, snoop, spyFrom the ODE community, based on WordNetadd/edit