I see people get stung all the time at the beach, my water polo coach is a head lifeguard for the state an had the craziest stories of people getting stung. One lady got stung in between her toes an it split her foot open to the bone.
I stepped on a ray and was stung in the achilles tendon by it when I was a kid. 20 years later, I was stung in the palm of my hand when I tried getting my hook out of its mouth. A friend was holding the tail/stinger wrapped in a towel but, it wiggled free and nailed me. Both were extremely painful.