wanktasy

Quite simply a 'Fantasy' that one might keep mentally stored away should they be short of any material over which to masturbate.
Etymologically speaking the word is a combination of the terms "Wank" and "Fantasy"; a simple yet pleasing origin.

Sebastian: Hey have you seen the newest series of doctor who?
Malcolm: Yeah I found the whole thing to be very disappointing.
Sebastian: mmmhmm, I miss Karen Gillan
Malcolm: I know she's a part of one of my greatest wanktasy.