Backpackin' it all in
If you think about it, something you put in your backpack is a lot like a hitchhiker hitching a ride on your back! Except it probably smells better than a hitchhiker and acts less creepy and you don't have to keep checking your rearview mirror to make sure it's not doing anything weird. On second thought, stuff in backpacks isn't at all like a hitchhiker. Never mind. Buy a bag.