I yell, "HEY!" as loud as I can, and use the entire lane in those situations.

Some people stop in mid-turn when they finally hear or see me, so I use the entire right lane. You know there is no car behind you in the right lane, otherwise the first car wouldn't be pulling out.

It's a good idea to keep the left lane as an option, too, in case they pull out all the way. I always like to have somewhere to go.

"Stupid" and "Defensive" are relative terms. How you define them depends a lot on your confidence and experience. Some situations that used to scare me to death before, don't even raise my heartrate now.