You can distance yourself from the source of such stories. You can also make it clear that you don't want to be involved in any way with this kind of inappropriate discussion.
Most mainstream movies avoid such explicit and disturbing content. The movie industry generally adheres to certain moral and ethical standards, and such a plot would be considered inappropriate and offensive for a wide audience. However, in some very low - budget or underground movies that are not subject to the usual regulations, there might be some extremely rare and inappropriate depictions, but these are not the norm.
Such stories often involve very disturbing and unethical content. However, in a civilized and legal society, prisons are supposed to be places of rehabilitation and protection of rights. While there may be individual untrue rumors or fictional accounts, the vast majority of prisons have strict regulations to prevent any form of sexual abuse.
While there might be some out - of - character and inappropriate fanfictions with this plot, it's important to note that J.K. Rowling's original works do not contain any such elements. Snape has his own story arc related to his love for Lily and his role in the wizarding war, not this kind of immoral behavior.
There are very few such stories in mainstream literature as it involves inappropriate and disturbing content. However, in some edgy or underground fictional works, there might be themes of coercion and abuse that could be loosely related, but these are not common or widely promoted due to ethical and moral reasons.
There are also heartwarming stories about friendship and family. Stories that show how people support and love each other in difficult times can be very inspiring and a much better choice than any inappropriate content.