---------------------------No Left Turn-------------------------------
It seems pretty straight forward. It's a sign with an arrow on it pointing to the left with a red circle with a line through it. Generally located at intersections with a high flow of traffic and no left turn signal. If you stop to turn left and wait for on-coming traffic, it backs up all the traffic behind you trying to get through the light. It's not rocket science... and yet it seems like there isn't a person on the streets who actually pays any attention to the sign at all.
I see this literally every day on my way to or from work. Often at some of the most inconvenient of intersections. And the real kicker is that no one enforces these signs, so there is no reason for people not to ignore them! I have seen a car hold up traffic while a cop is one of the people having to wait for the person trying to turn left. In fact, I've seen a cop do this himself! Although, it's kind of unfair to lump them into the same category because who knows his reason for doing it. He might have gotten a domestic violence call and needed to turn immediately, or maybe he just feels that since he's the enforcer of the law, he can break or bend the rules when it suits him... who knows?
I'm not really sure why the BMV bothers to make people take a test to get their driver's license. It's like any test you have ever taken in school. The minute the test is over and you get your passing grade, you forget everything that was on it. Although some things are just common sense. I'm not sure if it's lack of common sense or the simple fact that no one cares about anyone but themselves anymore.