My nephew cried when I threw out the fridge box, so now it lives in my garage
It sat in my driveway for 9 days because he turned it into a "spaceship" and made me tape a paper plate airlock to the side. Now I can't park in my own garage and he asks about it every single visit, so what do you guys do when a box outgrows its welcome?
That box is doing more for him than you probably realize, because at that age a cardboard spaceship he helped build beats any toy you could buy him. Instead of tossing it, maybe break it down and let him draw on the flattened pieces, then tell him the ship had to go in for repairs. He still gets the story and the memories, and you get your garage back.