Probably being held at gunpoint by a guard at a Jordanian airbase that I was inside of, doing a timed ruck march, as a US soldier.
I didn't speak his dialect, so I couldn't pick up much, but my gut said he was pissed he was on guard overnight and decided to ruin my night, too.
Only like the initial 15-30 seconds were really stressful, it was largely just annoying, since I couldn't communicate with anyone, standing there with my ruck on the ground and my hands up.