That is how they get broken teeth and smashed eyes. I tell them, remember there is much more surf coming in. Wait for another wave. Do not be a surf hog. I'm not sure that surfers today pride themselves in being good sports, but it wouldn't hurt.
Loose boards cause injuries, sometimes serious.
Few remember Robert Simmons, the great California surfer. However, he was killed by a loose surf board. It's not so important if you are a bodyboard - sponge doesn't hurt much. However, countless serious injuries have resulted from loose boards in the water. Unless you are surfing a deserted beach, a rare occurrence, you must have a leash.