Pisses me right off when people do either tbh, im very defensive when im driving, had some twat in a chrysler 300 try and overtake a long queue of 20mph traffic on the crosshatches on the A417 from gloucester, naturally when the traffic got to about 40mph he attempted to push infront of me (big green 4x4 with a trailer and SR on the back... not like he didnt see me), blasting the horn did nothing, so i held my position and by moving further into my lane he put a dent in his rear wing. Insurance company agreed he was at fault, i had to wipe his paint off my bullbar, bellend.
much like those who speed up when you overtake them, causing you to either increase your speed (i dont do more than 70 in the cage, too expensive on fuel) or reduce speed and drop in behind them.
i can deal with the ones who chop and change ASLONG AS they are situationally aware and dont change lanes without checking it is clear, the ones that do loose thier wingmirrors, simple as