This is one of those great pranks that only gets discovered a long time after the deed is done. Oklahoma State University officials realized that the letters 'OU' (the initials of their rival the University of Oklahoma) were gracing the side of their recently renovated stadium. Apparently one of the bricklayers working on the renovation project used darker bricks to spell out the initials of their rival. Unfortunately the officials are not taking the prank in very good humor. They've ordered that the offending bricks be replaced, at the expense of the contractor who did the work. Personally I can't see the initials that well in the picture that accompanies the article. I guess it's one of those things that you have to squint to see, kind of like the 666 on the side of the Alamo (though unlike the Alamo-666 thing, no one is claiming that demonic forces played a role in the OU prank).