Mike, I agree. I was rather thinking of using an international visual sign. A stylised jetski in a red circle with a diagonal line across it.
Heikevie. Thanks! You are more than welcome to play on your jetski over there. You are not inconveniencing anyone there and not trying to kill kids. Have fun - nobody is aiming any guns or crossbows at you.
You could forgive buksi for getting a bit uptight though. After all it was he himself, his kids and BigBoy's son, among others, who were in danger from these lunatics. They were all out playing together on buksi's kayak when these idiots turned up. They had to stop and move away from the killing field where the nitwits kept landing. AND they couldn't use their kayak any more because they would most certainly have been hit.
We all know what happened last year when a (probably the same) jetski wrecked someone's boat.
The only thing in the sea, outside Montri's, and they managed to hit it!