You see... those people you talk about and the people in this place are VERY different. The people in your school probably didn't have much empathy, probably didn't know how to take others seriously, probably some were bullies, immature ones, in resume... most of them were "normal" people and reacted like such.
The people here understand how you feel. If you ever have any problem, if you need support, you will be taken seriously, you won't be treated different, you won't be put aside or anything. Just because you see some jokes here or some random posts, it doesn't mean we are like those kids at school. If we were constantly talking about bad stuff, all the time, it would be really depressing... The whole forum is probably made of 80% negativity, so a few jokes, some clowning is healthy, in my opinion. Sometimes, a single joke here might cheer someone up, how isn't that supportive? how isn't that helpful?
I understand you and I understand how you feel, but please, try seeing the difference between those people at your school and those here. We aren't the same thing just because of a few jokes.
As for those who have posted pics and other random things, maybe you shouldn't joke at someone who's talking seriously. If someone here has something to say, it should be heard and respected (as long as it's not harrassment or something). If someone is worried about the jokes, thinks someone might treat them differently, coming here and posting those things might be like confirming that person's worrys. I understand perfectly that joking is healthy in a forum like this, but try to place yourself in the other's shoes for a moment. If you were talking seriously, if you were worried about something like this, would you like it if others start acting random? Wouldn't you feel a little paranoid about the situation?
Sorry if I sound too serious by the way. I'm not intending to make anyone feel bad, It's just my opinion.