Mine? Two parts.
I was at my wife's (then fiance's) college apartment with her and her roommates. It was a bit windy outside, and one of the roommates came in and didn't completely shut the door. I was talking to a different roommate who was about to leave when I heard the wind pick up. I reacted quickly, and pretended to open the door "with magic" as the wind pushed the door open. As the roommate's eyes went wide and her jaw dropped, I simple said "let me get that for you" and smiled politely like I simply had opened the door by hand (from several feet away). Mind. Blown. Absolutely speechless. Talked about it for months.
A few days later, the same roommate was there again. I was showing my then fiance how to throw playing cards. The roommate was in the kitchen across the main open living area from us, and was half watching what we were doing. I threw a card in the general direction of the roommate, pretty hard. It arched hard to the right, flew along parallel to the wall, lifted away from the wall just enough to clear the leading edge of a small whiteboard on the wall, and then jammed HARD into the far edge of said whiteboard, under the frame. It caused the whiteboard to rock back and forth violently, nearly falling off the wall, and making a very satisfying sound in the process. While the roommate was staring startled at the whiteboard and card, I regained my composure quickly and said something like "Just like that. You can kill a man with one of these if you can aim like me." It is not often that I freak someone out so bad that they don't think I am a normal human being, but this was clearly one of those occasions. It was SO HARD to hold a straight face.
Both instances? Complete accidents. I just happened to have the composure and swagger to pull off a trick when the opportunity presented itself. Those reactions were better than most normal magic I have ever performed, simply because they seemed absolutely impossible. I won't likely ever be able to repeat either, but I was ready when they happened.
// L