Yes they will just poop out the Aspen. One or two peices in the Tummy doesn't hurt. But I would definatly get the peice of Aspen out of his mouth asap. The longer it sits in there the more if an issue it could make getting it out. When I see Aspen in their mouth I wait till morning so they don't regurge and grab it out. You may need someone to help you bc its not a fin process. I've had this happen when I didn't grab out the water bowl before feeding and one of my females grabbed the rat and killed it in the water bowl and dragged it all over the cage.