Rated M For Mature

Resource: http://www.pcmag.com/article2/0,2817,2383978,00.asp
When it comes to ratings, video game retailers are more vigilant with mature video games than places that sell rated r movies or music with explicit lyrics.

The FTC recruited kids ages 13 to 16 to buy music, movie tickets, DVDs, and video games, without a parent, between November 2010 and January 2011. They were instructed to pick up movie tickets and DVDs for R-rated movies, CDs with parental advisory labels that warned of explicit content, and video games that were rated "M" for mature.

Apparently the kids were more successful getting movies and music they shouldn't be able to than video games with mature ratings.