It seems silly to actually mention this but some people have a hard time seeing the difference sometimes, I wouldn´t even be surprised if some people can´t even see the difference. Which doesn´t have to be a problem, but somehow usually does end up being a problem for him or her. Of course you can ignore other people and live in your own personal world, which is perfectly fine as long as you stick to that and not involve others in your personal world because that´s usually where things go wrong!
Porn isn´t real? Big surprise, they´re actors and the situations might seem believable (not often though) but it´s all acting. Which means people that have a hard time seeing the difference between fantasy and reality might think that what happens in porn might actually happen in real life, especially if they do exactly what they did in that movie. An example of this is subway groping, this is where some guys think it´s ok to touch women inappropriately in the subway. Of course it´s often crowded and I´m not saying that everyone is guilty, but when someone deliberately puts his hands on you then I´d recommend to scream bloody murder! It might seem like overreacting but I´ve heard plenty of stories where women are being groped by random strangers because they think it´s ok. Guess what? It´s not!
So how do you tell the difference between fantasy and reality? It might seem weird but it´s often best to assume it´s not ok than to assume that it is ok, which means don´t touch strangers just like that and respect some personal space! It´s true that some people have fantasies about being touched by a stranger but then when they´re in public it doesn´t mean they want to be groped by the first guy they see. The thing is that a fantasy is often a fantasy, something you fantasize about but it´s not always something you actually want to happen to you. Well there are exceptions but usually when it involves strangers or something extreme then it´s often just a fantasy and not something they would want to happen just like that. If someone does have a fantasy they want to become real then he or she will want to talk about that, make an agreement about it so you avoid misunderstandings.
Even when you know someones fantasy then that doesn´t give you the right to go for it just like that! In reality it´s wrong to put your hands on someone just like that, especially when the other doesn´t want you to do that. It´s better to be safe than sorry with these situations, maybe some will say that you´re a bit reluctant but it´s better to hold back and get permission than to go for it and be rejected!