I was at an offroad park and the sign clearly states helmets required, but 99% of the quad riders don't wear one and they don't enforce it. I came around a corner and there was an upside down quad with the helmetless, jean short, tennis shoe wearing rider with blood coming out of his forehead. He said, "It happened so fast". I said "That's why I wear protective gear" and then went and got help.
You know...I'm going to go out on a limb here and say that this type of quad'ing is okay. I love making fun of quad'tards, but drinking beer while playing in the mud without a helmet, just kind of seems okay to me.