Ferrets are wicked smaht.
Friends of mine had ferrets when I was in high school, and one of them learned how to get on the counter where the food was. He would go to the lower cupboards, open it with his nose, get inside, climb up to the drawer (just below the counter top) and then while upside down move his legs until he managed to open the drawer enough to jump out on top. I watched him do this, and as soon as he got on the counter I put him on the floor and watched again. He did the same thing, and I put him on the floor again. After the third time on the floor, he stopped, looked at me, and made a lunge for my ankles.
We would also put two ferrets on top of a blanket and lift and snap - not hard or anything, just enough so that they would bounce a few feet - they LOVED it!