Despite the enthusiasm from fans at the convention panels for Ash vs. Evil Dead, it seems whenever Bruce Campbell makes an entrance on stage for these things, some of the audience are booing him.
They're definitely yelling "Bruuce!" It's something of a panel tradition to do that to him at public events (I don't know if people got the idea from Bruce Springsteen's concerts, where it's an even bigger tradition to do the same thing, but if they did I'm amused).