Rats: Favorite Pasttimes.

Peter D. Sealey: "Chew and poop. That's all they do. That's all they're good for. Chewin' and poopin'."

You forgot "eat." In order to poop, they must consume.
You also forgot "sleep." Gnawing takes a lot of energy.
But yeah, that just about covers the extent of our little diva's busy days.
Too bad wild rats also have to constantly think about survival, about the effect of their next move, about whether or not that drop of peanut butter is safe or dangerous food, about shelter, warmth, continuation of the species...