"If you respect others and do not drop in on other surfers, you will probably have a good day. A smile and friendly attitude go a long way. When you go, paddle out humble and leave humble." - Aloha Surf Guide
"Don't drop in on or snake your fellow surfer. In other words, do not catch a wave once another surfer has claimed it by being in a deeper or more effective position at takeoff." -Surfline Surfology
This "common knowledge" amongst the surfing community can be applied to many other things in life, i.e. relationships and women, businesses and competition, or simply standing in line waiting for something. It's about courtesy, kindness,and respect.