A description of a person who has a wildly hilarious and twisted sense of humor and suggesting at least some degree of mental derangement, to differentiate them from the person who may just be seriously fucked up.
With all of her perfectly well-timed and lightheartedly sadistic workplace pranks relentlessly played on unsuspecting bosses and supervisors, and of course all of the jobs she sacrificed in the process of doing so, she was the poster person for being funny fucked up.