Very simple really, just say what the best/worst day of your life has been so far. Can choose more than 1 of each if you want, or if you only want to choose a best day but not a worst day, that's fine too. For me the best days have been the 2 days I watched Huddersfield win promotion. Because of that, it won't surprise you to know that the 2 worst days were the 2 times we got relegated.