Drivers who come racing up to you on the freeway/highway (being annoyed by tailgating isn't weird, but the behavior of the drivers is, so I say this counts):
Oh hello, Tailgater. I am sorry I am in your way, but there is a hoard of other cars ahead of us. You see, many of are driving to our destinations at the moment, so I'm afraid it'd be impossible to put pedal to metal in this case. Following me that closely isn't going to make a difference, and I'd rather not speed up and be only 5 feet behind a camper while going lethal MPH. Maybe when it's your birthday... you let me know then and I'll tailgate the person ahead of me as well, so together we can get to the exit ramp .004 seconds sooner. That'll be grand.
Eventually, they'll realize you're not about to speed up just for them and they'll change lanes and gun it. They will proceed for another few seconds before braking hard to avoid rear-ending the cars in that lane. See, crazy driver, I told you I was only going this speed because, due to traffic, there was no point going any faster, but you didn't believe me.
This happens way more frequently than I expect. Sometimes more than once a month. What is wrong with you people?
tl;dr I hate it when people tailgate you until the adjacent lane is clear, than launch themselves forward around you, only to brake hard 2 seconds later, because there's *GASP* cars in that lane too. Can't we all just drive safely and not die? I know we might have to get to work 5 minutes late every once in awhile, but isn't life more precious than that?