1. When the word is accompanied with 'The', it is referring to Brian Bell, the guitarist from the American
alternative rock band, Weezer. Fans devastatingly describe Bell as being "easily the sassiest guitarist to ever live. Sassier than Gwen Stefani and Prince combined." He repeatedly demonstrates his sassiness with moves like 'The
Impossible Bend' and 'The Power Rise'. Basically, if Brian Bell had a perfume, it would be named Sass in a Glass.
2. One who displays sass on a daily basis with no apologies. Note that true sassmasters do not claim to be a sassmaster, otherwise that just makes them a tool. They are humble about their
exceptional amounts of sass, which just makes them even sassier.