When I'm drawing, I erase like crazy and I flip my pencil over really really fast to use the eraser every five seconds, and sometimes it'll fly right out of my hand D:
Then I try to flip it over again, or erase without a pencil in my hand xD then just sit there like '...what just happened? Didn't I just have my pencil a second ago?'
Mine happened with a violin. In the sixth grade we had to take Strings and I was so clumsy that I couldn't hold my violin right and it simply flew out of my hands and hit this guy on the shoulder. The violin wasn't mine; it was school property but it was in a really sturdy case and nothing happened to the violin itself. My teacher looked like he wanted to murder me.