Alexandra Casuso was only 11 years old when Festivus made its TV debut on Seinfeld in 1997, so when she walked into her professor’s office recently and saw a pole in the corner, she had one question. ”He told me it wasn’t a stripper pole,” she says sheepishly — her first guess because she had never seen the classic sitcom. The professor showed her YouTube videos of the fateful episode — where Seinfeld’s sidekick George Costanza celebrates ”Festivus for the rest of us” with his family — and it clicked.