I would do it if I was that great of an artist. It would look so amateurish if I attempted it though and I would ruin my walls
Naaah, i thought about it too when i first saw it .. I think that'd make it look a bit silly and losses it's touch ..
That reminds me of the time my friend colored the walls of his garage with invisible ink. I didn't notice until the black light turned on and I was looking at the biggest phallically related word I've ever seen. But this is so much more cooler.