lets face it at 12 your just about to or have just hit puberty, you have just gotten out of elementary school and are heading into either jr high or middle school..... as far as you are concerned no more recess means no more recess teachers, that along with the other two changes means I can say what ever the "FUCK" I want when I want. ( that's the mentality of a twelve year old boy in the USA, I know because I was one as were all my male friends.)
That said, I was 13 when my mom first heard me swear, funny thing is, I stubbed my toe and said "shit" and she got all offended, and despite my dads insistence I didn't see why I had to apologize to her because I had sworn at the floor, if anything I should have apologized to my dad who INSTALLED the floor and even then an apology still didn't make any sense.