Yup, they do that. Our hamster cage had a 3 inch plastic barrier around the bottom of the cage and they still managed to have wood shavings and rodent poop all over everywhere. They also loved taking the shavings up into the Habitrail tubes and making their nests in one of the curves, therefore 1. making the tube impassable and 2. making cleanup much harder (have you ever tried to scrape dried hamster pee from the inside of a three inch curved tube?)I used to love to watch them stuff things into their cheeks. We used to give them strips of paper towel to use in the sleeping nest, and they would stuff a 1 inch by 1 foot piece of paper all the way into one cheek. One of them got found a way out of the cage once and took the time to fill both cheeks with food before leaving the cage and taking up residence in the 2" space between a cupboard and the wall next to it. Don’t think that wasn’t fun to clean up.