I used to threaten my kids that I'd take them to school in my giant rollers and a dingy flannel housecoat if they were late for the school bus. They were never late.
When my oldest was 3 he waited until I had already driven him to preschool and walked him to the door when he revealed "Mommy, I have on 2 pair of underwear" LOL, he thought that was the worst he could do, I always insisted they start the day with clean underwear.
Since your nephew's such a trickster, there has to be something that will 'get back at him' but only in a humorous way. Is there something he has that he keeps in a particularly neat and orderly way? Just go in when he's not looking and put them not in his order