It is not OK to touch someone else's private body parts.
Even if children feel uncomfortable in a situation and know that it's wrong, they don't always have the courage to stand up to an adult or someone older than them. Children have been taught from a young age to obey his or her elders. Parents have reinforced this time and time again and tell them to do what an adult tells them. This causes confusion for a child in a situation of abuse.
It is not OK for someone to touch his or her own private body parts in front of you.
Again, sometimes children don't see something like this as abuse. Even if the child feels weird about it and knows inside it's wrong, they sometimes doubt that it's abuse, and therefore don't tell trusted adults about what's going on.
It is not OK for someone to ask you to touch his or her private body parts.
Sometimes children think that if someone isn't touching them, it's technically not abuse. Even if they don't know what to think, their abuser may tell them something like this to convince them that touching someone else is OK. Because abusers are usually adults, or at least someone older than the child, they feel they have no choice but to listen.
It is not OK for someone to ask you to take your clothes off or to take photos or videos of you with your clothes off.
Adults sometimes use videos and photos to make the abuse situation more fun, or at least make it appear like a game. Young children sometimes like being photographed or on video, so adults will sometimes go along with it, enticing them by asking them to star in a movie. Though children may feel awkward or uncomfortable by being asked to be naked for the photos or video, it can still be overshadowed by the idea of doing it.
It is not OK for someone to show you photos or videos of people without their clothes on.
Even if parents tell their children that it's wrong for adults to touch their private parts, abusive adults may be able to convince children that looking at pictures of other people is OK because nobody is touching anyone. Children sometimes see rules as black and white without gray areas. They don't always make the connection that such photos are a form of abuse as well.