The abstact objectification of professor Severus Snape. This expression can be used to define a persons cunning, sneaky and greedy behaviour, similar to snake in the grass. It can also describe an action of backstabbish nature.
Fabio: Hey Yakopf, remember Sheniqua?
Yakopf: Yeah wasn't Pedro desperatly in love with her?
Fabio: Yeah, Micky fucking boffed the shit out of her.
Yakopf: That fucking Snape!
Fabio: He is the snapiest person i've ever known, snaping her
away like that.