In which Professor Snape loses control of an embarrassing situation

Professor Snape is caught short during a class with the gryffindors and slytherins and finds himself in a possibly very embarrassing situation. Will he be able to make it or will the strict and mystical facade in which we know Snape forever be broken. Just a silly fix i wrote because I couldn't imagine Snape in such a situation. JK Rowling's characters!