back when i was a noobe to archery i was shooting at my club with another noobe infront of me. As he was taking his shot he pinched the nock of the arrow with his index and middle fingers causing the arrow to flop off the rest. Instead of un-drawing and putting it back on he loosed it! it managed to fly almost at 90degrees to the normal direction of fire and rattled off the wall behind me having traveled rather close to my left shin!
i keep a close eye on him now 'cos he tends to do things like that rather often even now.