Told by Dan Barker on today's Freethought Radio broadcast.

There's a kid who is getting really bad grades in math, so his parents decide to try sending him to Catholic school hoping they can do a better job teaching him. Well, when his next report card comes they see his grades greatly improved. His dad asks him how he improved so much and he says "well, I figured out I better try harder when I see what they do to people that do bad in math." His dad asks him what he's talking about and he answers "Well, the first day I went in I saw that guy they nailed to the plus sign and figured they were serious about it."