I agree that you should actively play with your Grey. I have a couple of games that I play with Afie. In the one that is probably her favorite, I hand her and object and when she drops it I try to catch it before it hits the floor. As the game progresses she tries a variety of different tactics to try and prevent me from catching it. For example, holding on to the object a long time before she drops it, moving her head side to side and then dropping, or it or dropping it immediately after I hand it to her. If I catch it she will sometimes say "oh" in a disappointed voice and if it hits the floor she will sometimes give an evil sounding little laugh.