A rexie is a (disturbed) invidual afflicted with anorexia nervosa...and is proud of it. They're the kind of people who create websites the promote eating disorders and foolishly believe that they won't waste away and die.
"You can't force someone to eat. That's oppression!", quoth the rexie.
A person who has a strong physical thirst, need or craving for blood. Though this can be because of a sexual fetish, it's more likely to be related to physical or psychological problems (iron deficiency or the person believes they are Dracula).
"Goddamned sanguinarians...always bugging me for donations"