Lindenlabs, the creator of Secondlife is in a difficult situation. They want to allow humans to act out those fantasies which are hard or impossible to act out in real. That is all what the second life is all about. This is why you can fly, but this is also the reason why you can be a samurai, a ponygirl, a hooker, Gangster or Business Man.
However the problem is, that SL is for mature audience only, but that audience has different tastes. One is offended by the fantasy of another. And since SL has not yet a more fine grained labling system than PG and M, this causes problems.
Especially when you have a role play which is perfectly valid in real life (nobody can harm two adults playing teacher and schoolgirl) but which looks very illegal cause it is displayed so "real" on the 3d screen.
Anyway lately LL was annoucing that they have a hard time and might need to enforce their policies against "broadlyoffensive" content some more.
I just want to point to two pages where you can read up and contribute against that kind of upcoming censorship.