I was at some house at some stupid convention and some of my friends were there. We eren't aloud to go anywhere but the basement because the adults were so cruel. So we went down there to play video games and whatnot, and my friend's 10 year old brother closed the extremely very perfectly ginuinely clean and clear sliding glass door soundlessly behind us. Without us knowing. I got up to go to the bathroom, and ran full speed into what I thought was an open heavy glass door but was a closed heavy glass door. Bloody lip, knocked out for a minute or so. Very embarrising.