I had some of those those decorated boxes that you don't need to wrap, but I wrap anyway. 2 year old DS unwrapped his said "Ooh I got a reindeer" then set the box down and moved on to the next gift.
My 1-year-old did this last Christmas. He unwrapped a box with a picture of a kitten on it, yelled "Kitty!" and walked around with it for the rest of the day. (He liked it much better than the outfit inside, perhaps slightly to my mom's chagrin.
My MIL is the master of reusing things. Every year, I bake a ton of cookies and make a ton of candy to give as gifts, and buy tins to put them in for the recipients. And every year, she gets worked up because "I have a ton of tins you can use! I have a basement full of them! You don't need to buy any!"
She really means well, but every one of those tins has a brand-name on it and I don't want to confuse people ... and many of them are rusty from spending years in the basement.
My grandma pulled this off marvelously one year when I was in my early teens. I unwrapped a big, heavy gift from her one year, to find a box with a bowling ball on the outside. Now, grandma used to bowl, but it was never something I'd gotten into. I thanked her politely, though ... only to have her smile and tell me to open it.
Inside, in a box weighed down by bricks, was a tiny box with a beautiful birthstone ring in it. I've never seen her laugh so hard.
That was the last gift I ever received from her. I treasure it to this day ... and I think of the bright blue bowling ball whenever I wear it.