You've heard of elf on the shelf

then call em' out. break that dog from suckin' eggs.

I call them out everytime, unfortunately they're a hard-headed bunch

heres and idea,and i know it sounds petty but, have them give you a ride some were for a bit, and every time they take you somewere memorize their reaction to other people not using their blinkers. after you know what they say to it, you give the exact SAME responce when they do it. if they get mad just say "why are you mad, you say it all the time?" it may not be perfect but it's sure to help some.