The slogan? Or the actual thing? There's the Hogwarts' Crest with the houses and an H. Then at the bottom it says something like 'never tickle a sleeping dragon' or something.
The Hogwarts' crest design are the banners of the 4 houses, then an 'H' in the middle. There is a roll at the bottom that says the Hogwarts' motto : 'Draco Dormiens Nunquam Tittilandus', the Latin for 'Never Tickle a Sleeping Dragon'