I watched the last two debates. One thing about Bernie, he never gets flustered or raises his voice. Even when he should, gives the impression that he is easy to talk over and shout down.
BUT....during the last debate he was asked about his pro-communist comments in the past, especially in regards to Cuba. He said that Cuba had a wonderful education system, and that immediately drew boos from the crowd. Bernie immediately fired back "Oh really? Oh REALLY???" at the booers. IMO you could tell that their booing REALLY pissed him off, he took it personally LOL