We went diving from a large rib at Swanage a few years a go & they had a dog on board, it was a border collie & he loved being on board. He would pick up an empty water bottle & drop it between your feet waiting for you to throw it. If you took no notice he would tap you on the foot once, if you still did nothing he would tap you on the leg twice. If you still done nothing he would tap you on the thigh 3 times, then if you did nothing he would bight your n*** No, No not really!
He would go to someone else & start all over again until someone would throw it up the length of the boat. Apparently he has jumped off the boat sometimes when he got a little excited trying to catch the bottle.