*Not for Graveyard Book fic (though I kind of wish it were). The scenario is that a character (Jayne from Firefly, to be precise) is playing cards while under the inadvertant effect of a mind-altering substance, and can't remember the name of that "guy with the little hat" in his hand, but comes out with a short verse that contains the word 'jack' instead. I'm envisioning this rhyme as one he might have learned as a child and would remember under duress, so something fairly simple and with obvious rhymes would be good.
ETA: Thanks for all the suggestions! I ended up going with the 'futurized' 'House That Jack Built' idea, because I loved it :)