Here’s an interesting piece – sex with friends leads to more transmission of STD’s.

Essentially what happens is that people who have non-romantic sex with friends, tend to be more trusting that the friend is not carrying a disease.

But sometimes they do.

So it sounds to me like “friends with benefits” is a ploy for “free” sex.

Except there’s no such thing as “free”.

Hence, the STD.

In the end, you always pay.  It’s just a question of what currency you use …