Originally Posted by
control freak
Yeah, doesnt mean you have to be 18 to read, just that it's probably got sexual content and is adult in nature.
It's just a way of letting people know that the thread will contain elements of a mature nature and to use proper judgment when it comes to viewing it. Last thing anyone needs is to open a thread at work/school/around others and have there be sexual comments on the screen.

That could end awkwardly.
It also helps those who might be triggered by sexual content keep themselves safe.