So I just put a cardboard box in the cage with my guinea pigs. They are pushing it about and jumping around and chewing on it and climbing it. The thing is I know their cage is too small for them and I'm not sure if they are playing with the box or trying to get it out of there. Man, I need to give them more space... Poor little guys... 
I know how you feel. I have to keep my cat indoors in my apartment, and I feel like sometimes she's just going stir-crazy! I feel like such a bad momma...