It is a dangerous move to put a redhead in front of a brick wall because you risk making her disappear. It is like when a weatherman wears a green article of clothing in front of a green screen. If one is not prepared for it they could be in for quite a shock. Seeing a missing portion of a person who is acting like nothing is wrong is enough for anyone to accuse them of being a witch. In fact, I believe that is how the Salem witch trials started. One of those people tried that trick where you act like you can remove your thumb. From there things just kind of snowballed until they got out of control. Boy were the faces of the townspeople red when they found out about the misunderstanding.
Another word to the wise, I advise against standing a redhead in front of a green wall as well. People who are red/green colorblind will have a hard time discerning between the two and it will lead to the previously mentioned issue. The colorblind are a truly disenfranchised people in this country. No one ever worries about how their color schemes will affect them.
Photo Credit: Vikash Kumar Singh