Volatility trading, holding positions until expiration delivery, be sure to maintain a positive Gamma position. You don't need to be positive Gamma in every scenario, just maintain a positive Gamma locally around the current price. This small Gamma can amplify sharply as expiration approaches, and even a slight fluctuation in the spot market can trigger Delta Hedge. At this point, if someone comes to mess things up by crashing or pumping the market, it's quite popular. If you are intentionally or unfortunately holding negative Gamma at expiration, harboring hopes or fears of harvesting those last positive Theta. If a small fluctuation occurs that triggers your Delta Hedge a few times, you'll understand what pin risk means. It's quite comfortable. I've experienced it before. It's more intense than a Thai massage.