I walked in on my son when he was 3 years old, drawing on his bedroom wall with some crayons. When I asked him why he's drawing on the wall, he said he hates the wallpaper lol (he loves it, he picked it 2 months before from fucking Laura Ashley)
Just a thought though - maybe they draw these monstrosities with tattoos because they hate their bodies. Most people on these 'Worst ever tattoos' posts are usually pretty ugly.