I absolutely cannot stand it when people refer to graphically violent games as "mature games". Of course I know the ESRB rating for games with graphic violence is "Mature", but it still bothers me when it's used in speaking about such games.
The reason being that I see nothing truly mature about playing a game like "Manhunt". In fact, I think it's about as immature an activity as graphitti on a public building, or fights after school.
If someone wants to call something "mature", they should refer to something like saving some money in the bank, or buying a house, or raising a child in a proper way, or getting married. Those things are mature behavior, not savaging a dude in a jail cell in Manhunt. /rant