This humourous design, "I have CDO. It's like OCD but the letters are in alphabetical order. (Like they should be.)" is meant to poke a little fun at Obsessive Compulsive Disorder and those of us that have it just a little bit. Do you alphabetise your soup cans? Fold your towels only in threes? This shirt could be for you!
Note: OCD afflicts millions of people and the disease itself can be debilitating. We don't mean to offend anyone and have, in fact, lived with it all our own life. We also feel like the best therapy is laughing at ourselves once in a while, and that's the root of the humour in this design.