I did encounter someone taking it to new levels yesterday. I was waiting to make a left turn. There was a driver across from me waiting to make a left turn as well. Although there are no turning lanes at this intersection, there's room in both directions for cars going straight to pass on the right. The driver across from me was giving me polite toots on his horn encouraging me to go ahead, completely oblivious to the steady line of cars that was proceeding through the intersection on his right. I shrugged and pointed. Got off the saddle and put both feet on the ground. HE PULLED FORWARD AND TO THE RIGHT TO BLOCK TRAFFIC! and then continued waving at me and politely tooting his horn.