This is a much debated issue.

Traditionally, Flaperons are used to lower the "neutral" position of both ailerons so that the ailerons effectively behave like flaps. This is exactly what you thought flapperons are.

In the 3D world of flying, the elevator is not enough of a control surface for some, so they couple the ailerons to the elevator channel so that when the elevator stick is pushed forward (down), the ailerons move UP, and when the elevator is pulled back (up), the ailerons move down. This makes the plane do more aggressive loops. For example, when you want to do a loop, you pull back on the stick. The ailerons behave like flaps, and increase the lift over the wings, pulling the plane UP. This amplifies the work done by the elevator.

Now, the 3D people like to call their setup "Flaperons" as well, but the purpose of their setup is totally different than the traditional motivation.

gus