So yeah. Post the derpiest/most facepalm moment you've had in LoL. It can be a time when it benefits you or it can be a time where it hurts you.
So here is my first one: I was once laning as morgana against a Ryze who played a lot of Coop VS AI. I Qed him, but missed while he was at 1/4 health. I accidentally used my W on him since I thought my Q would hit. He never laned against a Morgana so he stood right in it. He said in All chat "You can't kill me with that black stuff". Two seconds later, "You have slain an enemy!"
Second one: We had our turrets down, but we just scored an Ace. We didn't notice a big minion wave come into our base and they destroyed our two Nexus turrets. We rushed back to base trying to kill all the minions, but the nexus exploded and we lost .
Post some more here!