That waist-high drawing you find all over everything the minute your turn your back on your child. It's like your house/car/clothing/table/tablecloth/other child* is Rome or something. See also: "500 crayons, but one permanent marker: ability of child to find".
And am I the only one who paints over the marking on the wall rather than trying to clean it? Sorry folks with wallpaper, I win this round . . .
*Family story: younger sister is being too quiet. Mom checks in on her. Finds her marking up the wall, the crib, and the even younger sister in the crib. Purple it was. Permanent it was. Yep, mom had to show of the purple head baby for a while.