I remember a buddy of mine in junior high school showed me at the local swimming pool how you could stand in front of the jet of water pumping into the pool below the surface. We'd hang on to the edge of the pool and act like nothing was going on. One day after we'd gotten off, we looked around and noticed the lifeguard up on the stand had been watching us. He was laughing, and gave us a thumbs up. He told us later it was a pool "tradition", and the lifeguards had been doing it for years after hours.
