For me, the weirdest thing to ever happen was an arrest of the player sitting next to me.
...
Holy moly. I played in that event in the U1600 (tied first) and don't remember that happening. Must have been after I finshed a game and left the room. As I recall Wojo won the event easily.
This is pretty embarrassing but whatever.
the position is below. I was playing in a tournament and realized this was a completely lost position. Somehow, I determined that Rc8 was mate. I whispered, "omg, that's checkmate, and I played the move." my opponent looks like he got a heart attack. Until the guy next to me told me that's an illegal move because my rook is pinned to the king. He obviously thought I was an idiot. But my opponent's like "dude, you scared the crap out of me." I felt so bad lol but it was hilarious..and I'm so idiotic haha
It's actually illegal for the guy observing to say anything, if your opponent did not see the rook is pinned and thinks the game is over and shakes your hand.. you actually win the game believe it or not.
As opposed to the observer, if he said that and he is playing in the tournament, there would be a penalty on him.