I just say "shush, wait" I'm the guy most people come to with their doubts (don't know why), and many times there are 3 or 4 people talking to me at once. Then I just put my head on the desk, and they all stop
. Then, I listen to them one by one. Unfortunately, I can't tell them to stop, I don't have the heart. I just get excited when somebody asks me a problem that I know how to solve, and even more excited when it's one that I can't solve :P.