The whole secret of raising a fart in class is to make it sound as if it is punctuating, or commenting upon, what the teacher is saying. Timing, not ripeness, is all. 'And since x tends to y as c tends to d,' Fred expounded, 'then the differential of the increment of x squared must be... must be... come on, come on! What must it flaming be?' Here was the chance to to give my version of what it must be. I armed one, opened the bomb bay, and let it go. Unfortunately, the results far exceeded the discreet limits I had intended. It sounded like a moose coughing.