1. to pass out or sleep on a mattress that is not the one you normally sleep in;
2. often involves sleeping on a mattress placed in a bathroom or shower room;
3. often involves the process of puking, peeing, or crapping yourself, or a combination of the three--also known as the trifecta.
1. the location of the zookie;
2. usually an old mattress only suitable to sleep on when blacked-out.
When someone gets too drunk to sleep in their own bed (for fears of dirtying it), a friend would lead him to a zookie mattress, where he is free on any normal inhibitions, and may soil himself as he pleases. The mattress can simply be hosed down the next morning.