So as I am sure most people experience, whenever I open the fridge and crinkle a bag, my guinea pigs wheek with anticipation. This leaves me feeling guilty like I am getting their hopes up for nothing! So now as I prepare a salad and carry it to them, I whistle. They whistle back and run to the side of the cage to greet me! Fewer false hopes every time the fridge is opened for them. They have trained me well.