Don't call let's or "ball on", (what an irritating term), for other's courts, (unless it's a really hot chick, who isn't a tournament player, know any better and you are trying to chat her up and ingratiate yourself with her). They have opponents with eyes like yours and can see just as well as you can. This is a good reason to be nice to your opponents. I "play" with a few rec players, who never look back at long serves to see if they are rolling back behind them. I'll warn them the first time, but if I learn that's their habit, I don't warn them anymore. I don't know if they are being stupid or macho or both, probably both. If they step on it and get injured I DON'T CARE! If for some reason they think I should have warned them, I will just say, "Sorry, couldn't see it, net was in the way." Survival of the fittest, Darwinism at it's finest. The good news is a fractured ankle heals stronger then new in a few weeks, it's sprains that can take up to a year until you can't remember which side it was on.