Most Painful: I have forgotten my bitcoin PRIVATEKEY in December last year, This is the time bitcoin go to moon lol
Sorry for that painful event on your life. You missed the moon but I guess you still managed to hold some bitcoins on your other wallet right? And you learned the lesson that you should keep your private keys properly with back up.
Happiest: I participated in an ICO investment project and it was x20 after going to the floor for some time. It helped me solve a lot of problems.
What is this ICO you participated and how much was your initial investment? x20 profit is a nice profit.