Yeah, there's always some people who won't make fun, instead they help. Your post remind a incident happened in my first semester during viva exam. We had a chemistry Viva exam and our professor was a women. I already informed my friend that if we go to the professor together then please told him following "you please told him that my friend (my name) is a stammerer. She asked me a question and when I about to say something I realised i couldn't speak; just mumbling like "this... this...is...s..s.s.". It was really embarrassing for me. My professor realised that I'm not well. She told me not to worry too much, and take as long as much time you can...I started speaking slowly.. mumbled for few times...and completed my answer in close to 1 minutes.... I really thank full for such people who understand others people problem.