Writings on the walls

When did this get to be a thing? Words painted on the interior walls of a house. Some are sweet: "Always kiss before saying goodnight" painted on the master-bedroom door. Some are weird, such as the Star Trek (original series) quote that I can't remember. Some make me think, such as "Get naked," painted in very large letters above a single woman's bathtub. To each his own.

Speaking of painted walls, almost all houses have very neutral colors on all walls. But there is one room I won't forget. It was painted hot pink, a real assault on the eyes. Plus, it had a chain lock on the door -- on the inside. I'd like to know the story behind that one.