Earlier today I was walking my dog in the park and intermittently chucking a ball for him with one of those plastic thrower things. A man with a collie passed us and, as I threw the ball, he said "Use your arm." I didn't hear him properly at first so just randomly said "I know" then he looked confused and passe d on. Is only when I saw him chucking his ball with his arm that I realised what he had said. Is it a thing not to use ball chuckers at the park or generally?