I found this to be pretty interesting. Did you know that you can pretty much remove sharpie pen ink from most surfaces with baking soda toothpaste? Nor did I. But you can.
I never actually really thought about it much, but it makes sense that baking soda would foam up and probably allow you to scrub a bit more. The toothpaste in the video actually has peroxide in it too which does probably break away some of the ink. Heck, you figure that it gets tough on your teeth so why not on that wall of yours since your two year old decided to work that wall like Van Gogh.