How do I get morbidly obese quick?!

Drink olive oil like it's gatorade.

First you're going to want to stop exercising. Forget about using the legs your were born with, go out and by a mobility scooter for those very short trips, and use the car to get you everywhere else.

With all the spare time you now have seeing as you can no longer exercise, you're going to need a hobby. If becoming obese is the goal, I suggest eating as a great fulfilling hobby that you can do all day long. Ensure you go for high energy foods such as potatoes, pasta, breads & plenty of refined white sugar products like candy and soda. Ensure your portion sizing is huge, the greedier you are the better.

Now that I've answered your question, explain why you would want to risk your health like this? I strongly advise you not to undertake the above mentioned tips on how to become obese.

Deep fry potatoes in cooking oil with white flour, put some sugar in it (or a lot) and EAT.