There are songs which are a turn on just like that, by themselves. As soon as I hear them I get the impulse to put my hand down my jeans. These are songs that have the perfect rhythm to have sex to. They're slow, almost a pounding beat to them.
Some are faster but are erotic for the sensuality of the voice or for the melody which runs though you like a wave of spasms.
What kind of music would you fuck to? Is it slow and controlled? is it heavy and violent? is it fast and playful?