Noah's "coloring" on my wall

Michael's family is coming to visit tonight, so Noah & I were upstairs. I was putting sheets on Rebekah & Brian's bed and Noah was watching the Wiggles in the tv room...or so I thought. I literally left him alone 2 minutes...entered the room to find that he had made a masterpiece in pen....ALL OVER MY WALL! I bet there was 15-20 feet of wall space (of course, the biggest wall in the rooom, mind you) that had pen scribbles all the way down the wall. I tried not to freak out. I used the Mr. Clean eraser thing out of desperation, and it took about 90% of it off the wall...along with a little bit of paint, but it's not noticeable now like it was when I first walked in the room. Noah kept saying, "Happy Happy, Mama." I said, "No, Mama not happy." Not the end of the world, but surely not the easiest way to start the day either. Oh well. After that drama, Noah & I had a picnic in the small hall preceding his room & he went off to nap.