Ever since the first humans started drawing in caves, there were some cavemen who drew dodgy pictures. The pyramids probably have some secret chamber of inappropriate hieroglyphics and when the Romans started building walls, people started writing explicit things on them. Fast forward a few centuries and we all remember someone at primary school who found it hilarious to draw specific things on other people's pencil cases. Creating and sharing dodgy content isn't new, but technology has certainly given 'dodgy' a whole new platform.