futter,v. To engage in sex without sentiment; to have sex merely for the physical experience of it. ______________
"Man is only looking for a hole; woman is only looking for a pole!" ~ old Muslim saying
As those who have had sex know (of whom I am not one), sometimes we just want to stick our poles into a hole, stick a pole into our holes, or some other combination thereof just for the fun of it. That's why we futter, to scratch that itch without bothering with getting all affectionate with the partner. On the other hand, there's coition, in which the sex is an expression of love and mutual affection. It's like the difference between eating to satisfy hunger or for the fun of it and eating socially, such as with a romantic dinner.
The West tends to condemn futtering, in favor of coition, if sex for non-reproduction is accepted at all. That's probably because the stick up the rear gets in the way.
My Source: The Cradle of Erotica, Allen Edwardes and R.E.L. Masters