Frustrated and 'no longer fooling around,' the nation's substitute teachers publicly demanded Monday to know the identity of the student who threw that. 'We are really starting to get fed up here,' said Paula Jenkins, president of the National Association Of Substitute Teachers. 'We want to know who threw that right now, and we are not kidding.' If the perpetrator is not revealed within the next minute, the substitutes have threatened to leave the nation's regular teachers a scathing report detailing the misbehavior of U.S. students while they were out. 