Herman's Head (1991)

Herman Brooks is an aspiring writer working as a fact-checker at a publisher. While dealing with life in the big city, his inner thoughts are played out by four characters representing his intellect, fear, compassion, and lust. His "outer world" consists of a trivia-trove boss, two female co-workers, one mouse-ish and the other a social-climbing bombshell, and a best friend whose both a successful writer and a sexist pig.