(verb) Origin is from the gay slang underworld: Wearing extremely tight trousers that allow everyone to dig the general size and shape of the paynus, e.g., Tom Jones in the 1970s.
Shit, Robert Plant was featuring his trouser snake in them tight blue jeans.
It means the shiznit plus. Ne plus ultra, the best, the GOAT.
Marcia Resnick? The best photographer; the shizniticus.