Double Feature Event
Opponent was able to exploit a bug that prevented him from having to discard more than 1 card. 1st time I cast Aim for the Head, choosing Exile 2 Cards. Opponent cast a Flash creature, then only discard 1 card even though he still had more cards in his hands. The second was activating Evolving Wilds which bugged No Way Out, and only discarded 1 card with more left in his hand.
All the opponent had to do was add something to the stack, then discard only 1 card instead of 2.
I do believe this happened in a game before as well, but I am sure about the second game.