The oldest most comfortable shoes they own. I bought our youngest a pair of new sneakers. She lives in cowboy boots all year, even in the hottest months and I thought she would die wearing them at wdw. By day 2 of a 2 two week stay she was miserable. We had the grandparents overnight her old boots and all was good. Yep, our 4 year old spent over a week in cowboy boots, not one blister. Crazy