Warning Labels - Let Hilarity Ensue

At work I came across something I found to be fairly amusing: A book with a "warning" label . . . or perhaps "rating" label is more precise. It is reminiscent of how TV rates viewer programs, from child safe to all that fun stuff (I can't recall an exact one but I think there was one that have like 13 or 14 on it saying it was unsuitable for children below that age) and of how videogames are rated (E for everyone, M for mature).

Wolf Pirate Publishing is actually putting labels like these on the back of their books. Really. I just laughed when I saw it. Probably not as funny as I am making it out to be, but it seems ridiculous to me.

So, on the back of The Angel's Iscariot, there is a box with a big, bold M next to another box that descries "Contains: Adult situations, violence, and mature subject matter not appropriate for young readers." And on the back of The Repossession is a box with an R next to another box that reads "Contains: Adult situation, violence, sexual content and mature subject matter not appropriate for young readers."

Apparently sexual content is the only thing that is the difference between an R rating and an M rating. Shouldn't that be an X rating instead? And, truthfully, this stuff is found in basic sections, not children's sections, so is a label even necessary?