How did I get in trouble from this?

[Jonathan King]

So I'm a 17 year old guy and I got in trouble for having my twitter profile picture of myself with my shirt off showing my abs. Apparently I got in trouble for that. Also, I was posting negative tweets about grade 9s, because no one likes some of them. How could I get in trouble for that? It's a social networking site that's not related to the school in any way. And to top it all off, I'm not even allowed to swear. Apparently I could get suspended for swearing and insulting on twitter if I did it again. I rarely swear on Facebook in my status' and I've never got in trouble for that... Can someone help me?