Fantasy sex covers a wide variety of erotic images, thoughts, memories, or dreams. Due to the nature of some fantasies, the actual putting of such fantasies into action is far less common, due to cultural, social, moral, and religious constraints. Fantasy porn breaks this barrier by incorporating social taboos and roleplay scenarios to enhance arousal. BDSM, group sex, voyeurism, and exhibitionism are all common themes in this XXX niche.