Karens enjoy being given attention (albeit negative), and unfortunately, it tends to come at other people's expense. Especially those who work in customer service, AKA baristas, servers, retail workers, etc. This Karen picked the wrong day to mess with this barista, as it was the employee's last day. Karen had a constant rude, demeaning attitude, making employees and customers hate her alike. So it couldn't have been that much of a surprise that this employee snapped. But of course, we're talki…