a girl who looks pretty good and flirts with a bunch of guys but doesn't actually like them or want to have anything to do with 'em; leads people on

ex1. lifeguard who'll let you put your feet in the pool but won't let you jump in.

ex2. forest ranger who give matches to a pyro and tells 'em not to burn the forest down.

Someone who flirts and gets off with lads, but doesn't actually shag them i.e. leads them on!