Updated: Nov 8, 2019
Just kidding, there are no cheat codes :(
That being said, have you tried using two fingers to draw or erase? It creates a line between your fingers, allowing quick creation of filled areas, squares and triangles too.
“I still don't understand why we have to have a quotes section, it's not like anything we have to say is really that interesting..."
In addition, hitting the back button on the phone allows you to quickly clear the screen and return to the editor. Just don't do it by accident...
Weird things to try
Try adding a photo of yourself, then crop your face and save it as a Doodle. Then you can add your face to ANYTHING YOU WANT!!! Wow!
If you want to simulate a whole batch of characters, use the image loader multiple times and just scale down each image. There is no requirement that just one object is created.
More tips to come!