This article on April Fool\'s Day pranks quotes a Wayne State professor...Jerry Herron, director of American studies at Wayne State University in Detroit, recalled his childhood in the 1950s, when \"elaborate and sometimes cruel\" jokes were common. \"Pinning signs on people\'s backs, telling kids they were wanted in the principal\'s office - those kinds of things happened a lot,\" he said. Herron recalled one unfortunate schoolmate whose practical-jokester mother deliberately packed a rotten egg in his lunch bag one April Fools\' Day. The professor attributed the lull in April Fools\' activities in part to the holiday\'s lack of marketability. \"What kind of greeting card could Hallmark sell?\" he asked. \"Something that explodes, maybe?\"