dragged

So the other day I was doubling with my friend and we had a mix up in communication and he ended up right behind me for some reason and fell, but when he fell his rope handle got wrapped around my boot and before i knew it was there i let go of my rope and i got dragged about 30 ft. until my board wripped off. Im lucky my ankle didnt break or something

Has this ever happened to anyone? How can we communicate better when doubling?