I remember seeing this poster when I was a kid standing in line at a movie theatre. I was amused by the contrast between the happy kids with movie-viewing giraffe for the Rated G movie and the dodgy looking unaccompanied man with sunglasses (well I guess I imagined the glasses) at the Rated NC-17 movie.
I happy to say that, over a decade later, movie rating explanations are still amusing. Behold: the Dutch system.
There are six possible evils in any given film in the Netherlands. Here are the logos they use – and my interpretation of each logo’s meaning:
This logo means there is liable to a rootin-tootin smack down in the film. This is also known as “violence”.
This “sex symbol” means that the movie will contain sex – and that the participants will not be wearing shoes.
The movie will contain giant blood-thirsty spiders. Arachnophobes beware.
Shots. This movie will have sharp syringes.
People feeling isolated / alienated. It will be like junior high – or is a movie about people in junior high.
This movie contains scenes of food poisoning or other ailments that induce the vomiting of large zig-zaggy worms.
It turns out I was wrong about most of the symbols – even when I was actually trying to think of what they’re supposed to represent. It wasn’t until I figured out how to spell “kijkwijzer” that I actually got the true meanings of these logos. (Language note: “ij” sound like “eye” in Dutch. Thus the Nile river is spelled “Nijl” here.) Anyway, kijkwijzer.nl explains what they actually mean.
Interestingly, the Dutch system allows even non-industry people to see the exact test for determining which warnings to display. For example, question 3.3.6 (used to determine whether the “fear” warning need apply) reads:

Are there extreme horror effects caused by the actions of recognizable living beings such as people, animals or insects?
. . . the term extreme horror effects includes . . . the man with the axe in The Shining