That Guy with the CMB

Whether it was a personal project that bombed or a school assignment that you got an F on, what was the biggest waste of time you've ever put a ton of work into and it just failed? Bonus, how mad were you about it? I'm writing this because I wasted three-and-a-half hours doing something for school for an F...which isn't the biggest waste of time on a project I've experienced, but it's definitely up there. I actually strained my eyes staring at an off-brand Microsoft Word for three-and-a-half hours straight and typing my heart out, but it got an F because it didn't directly respond to what the teacher wanted. I felt as if the teacher were hiding a paper with the exact words he wanted on the research paper but he didn't tell me. It hurt my self-esteem, too, because I typically rock the house on essays.