Another alternative to the interpretation of Draco Dormiens Nunquam Titillandus can be the following: each of the four words represents a particular House. Draco as "dragon" would therefore represent Slytherin, since there is a relation between dragons and serpents, and the serpent is Slytherin's animal. Dormiens as "sleeping" would then be an equivalent to Hufflepuff, if we relate the house mascot, a badger, to sleeping. I'm not saying badgers sleep through all of their lives, but they are nocturnal animals, which means they're active during night time, and so they usually sleep, while humans, snakes, eagles, lions, etc. are normally awake.
Next, we have Nunquam as "never," which could stand for Ravenclaw. Before you start laughing, I realize how ridiculous this may sound, but it's the only connection I could come up with. If we focus on the raven instead of the eagle (which is the official house animal) in regards with Ravenclaw, Edgar Allan Poe's famous (and my personal all-time-favourite poem) "The Raven" comes to mind. Those of you who are familiar with the poem will surely recall the well-known "nevermore" that the speaker of the poem repeats (correct me if I'm wrong) eleven times. Twelve times actually, if we count "nevermore" and "never" as well. That's more than enough for anyone who has ever read the poem to subconsciously connect this particular word with it. Ravenclaw = never(more) = Nunquam.
Now all that we're left with is Titillandus as in "to tickle." This can be related to Gryffindor (though not too much to its lion), since Gryffindors like to go looking for trouble, or better said, "be brave," tickling dragons if they find it necessary. Moreover, Gryffindors like to joke around (remember George, Fred, Lee, the Marauders, etc.), which is not a characteristic that can be as easily applied to any other House. And tickling is, of course, a thing one usually does in a joke, to have fun.
Es gibt noch mehr Theorien dazu.
Quelle: http://www.mugglenet.com/editorials/edi ... da01.shtml