Only once, and it was intentional.
Basically, one of my friends got a nosebleed at school and I thought it was the coolest thing ever. That night I asked my mom how people get nosebleeds, she told me that it can happen for various reasons and named some, one of them was "being upside down for too long." So, as soon as she left my room, I went to the edge of my bed and hung my head over the side while laying on my back; I sat like that for a solid 20 minutes while pinching, slapping, rubbing and blowing my nose. Eventually, I got a nosebleed and my life goal was complete.