An interesting theory in psychology/neuropsychology has to do with how the brain transfers arousal from a negative to a positive experience or feeling. I suppose it could work the other way too, but the gist is about going from a negative experience-emotion (like fear or anxiety) to a positive experience-emotion (like relief, pleasure, sexual arousal).
Basically it becomes possible for the brain to associate one type of arousal, originating from a certain sensation or perception, with other salient sensations or perceptions than originated it. The idea is that the brain interprets arousal in terms of bodily signals, for example if we are outside and suddenly see a snake on the ground next to our foot; immediately this perception causes a fight or flight autonomic arousal to occur physiologically including release of stress hormones, heartbeat increase, etc. Immediately the brain interprets this autonomic arousal in a negative way i.e. fear. But then a second later, we realize it’s not a snake but only a stick. The physiological changes that had been subjectively experienced by us as fear are still present in the body for a short time, but we are no longer as scared, rather because we now feel safe the physiological arousal can be re-interpreted by the brain as a positive subjective experience i.e. we may feel relief, gratitude, happiness, excitement, humor. The autonomic arousal triggered things like hormone release, which at first was experienced negatively and then later the same autonomic arousal responses were experienced positively.
This also can explain why taboos are so fascinating to us, including swear words and also sexual taboos. And it can explain why we feel excitement at watching horror movies. We may feel some fear or negative subjective emotion but more so we are also feeling positive subjective emotion as what may have begin as physiological arousal in response to a threatening stimulus quickly sublimates and is re-interpreted neurologically or neurochemically into pleasure. Likewise, the thrill of potential danger or of violating social taboos can lead to increased sexual arousal, or just increased arousal and pleasure overall. Like if you ever stole something from a store and got an adrenaline rush and it felt good.
The good feeling that comes after the re-interpretation, via the subsequent excitation transfer, can serve as its own pleasure reward mechanism and become reinforced over time. We may adopt patterns of risky, bad or immoral behaviors because of the thrill and later relief-excitement adrenaline rush it gives us when we get away with it. Or, if occurring in close temporal proximity to something that gives us pleasure, like sex for example, the sexual arousal itself can become paired over time with taboo sensations, images or thoughts. Like rape fantasy, incest, etc.
Neurologically there have been studies done that demonstrate when someone is engaged in performing tasks while exposed to neutral stimuli but then is subjected to the stimuli of a taboo word or image, their task completion rate slows significantly and different parts of the brain associated with inhibition light up. There is a particularly interesting link proposed between areas in the frontal cortex and the amygdala, from what I understand anyway, whereby the exposure to a taboo causes us to internally repeat the taboo in a non-conscious way, as part of a pre-conscious neurological process, and then this signal is sent to other parts of the brain involved with assessing social situational appropriateness. The brain basically internally models the reproduction of the taboo in its own virtual neurological space, then sends this data to a part of the brain that can assess whether or not, given this particular social situation and its meaning, it would be appropriate to express or verbalize that taboo, to repeat it. Then we either act to repeat it or we self-inhibit and do not repeat it.
Example, we might say the word fuck in a context of being around close friends whom we know don’t care about that word or may think it’s funny, but we might not say fuck in the context of a job interview or around our immediately family members.
…So excitation transfer can occur in different ways. It can lead to transforming stressful emotions into positive emotions quickly or over longer periods of time, or it can cause mis-associations between disgusting or immoral things and pleasure from watching a movie or having a sexual experience via shifting the arousal from a negative to a positive interpretation, or it can initiate a self-inhibitory process that depending on social cues will either cause us to repeat-reinforce a taboo or suppress this repetition-reinforcement.