So, this week my brother was playing the classic Super Mario Bros. 3. And we noticed how the Boos stop and shield their face when you look at them, but when you look away, they chase you. At that point, I had a silent revelation:
Can't look at you.
Don't attack when you look at them.
Attack when you're not looking.
The Boos are obviously relatives of The Weeping Angels. So any image of a Boo becomes itself a Boo. And you can't look them in the eyes, because they will infect you by implanting an image in your mind.
Muah ha ha! Sweet dreams, Mario fans who are also Whovians!