I've worked at my job a year and 4 months. I hate the job but I'm well liked. I gave my manager 3 weeks notice for 2 days that I need off. My plane tickets have been purchased and I'm going to attend a holiday charity event. My manager has denied my request to have off because she's already given 2 other people those days off. She asked if I could change the dates but I can't because of the event. My coworkers have told me to just call in on those days. I want to, but I'm also scared my manager will use it as an excuse to fire me. Do I go or not go?