How do I get a friend to learn to signal their lane changes?

I've got a friend - okay, actually, my manager - who drives kinda like a derp. Sometimes we leave at the same time, and I can see how he drives. It drives me nuts to see him ';drifting'; into other lanes without signaling. I know it drives most other people mad as well. I've poked him endlessly about his goofy driving and signaling and yet he totally fails to give a crap. Anyone have any experience in getting someone to change their hazardous driving habits?How do I get a friend to learn to signal their lane changes?
You are not your brother's keeper. You have already informed him of the error of his ways, there is nothing more you can do. You need to accept what you cannot change.How do I get a friend to learn to signal their lane changes?
simple

Car crash

it makes then change their ways
Set up a time just after lunch because your friend will have nothing to bother him..



Make sure you come armed with information, it will make your conversation go more smoothly. You can even create a list of specific questions you want to ask him..



Be blunt, after all you are the one that is trying to help him...
why dont you just tell him that he needs to use his blinker?
Not your problem. Just mind your own driving and stay out of his way.
I agree with the others who say NOT YOUR PROBLEM! why do you feel the need to try and control other people's behavior???



If it were ME, I would tell you to go **** yourself. Maybe HE will too.
you should ask him how he got his license?
if you ride with him, constantly nag him about signalling.

i. if he drifts out of his lane, say ';watch out for that car'; even if there is no car



if not, show him accidents that were caused by inattentive drivers drifting out of their lanes.

if all else fails, then the accident he will cause will change his ways