I hate these jacklegs. You're in the right lane, they come up behind you in the left lane and squat right in your blind spot, and eventually run you into the back of whatever car is in front of you. You then either have to stomp it and jump in front of them to pass the car, or break the cruise and slow way down while they pass you so you can get over and pass as well.
That, and people that ride my *** in the left lane while I'm passing an 18 wheeler. I'm not going to cut off the big rig by jumping back in the right lane immediately in front of it, but as soon as I get far enough in front to get over, the tailgater behind me will jump in the right lane and come screaming past on the right, often shooting a dirty look or a finger. Even if I signal that I'm intending to get over as I pass the semi, they don't care, as soon as they have a space they'll do it and cause the 18 wheeler to hit the brakes. I've had multiple 18 wheeler drivers tell me that's their biggest peeve, when someone passes them and immediately gets in front of them instead of going on ahead a few lengths before moving over.