Can your pets open the fridge?

My cats haven't learned how to open the fridge door, luckily (or if they have, they also know to close it afterwards and not leave a mess). But when I open it, my younger cat runs from wherever he is to stand himself on his back legs and peek inside. I think that if I left the door open long enough, he would try to jump in! I have one of those fridges where the smaller, bottom part is a freezer and the bigger top part is the fridge, so even though they can reach it, I think that it would be hard for them to open it.