People who have to competitive, when it serves no purpose except to demonstrate they are rude. Like when you hit the button to call the elevator, and just before it arrives, one other person walks up to get on, then they cut in front of you to get on first (hello, getting on fast doesn't do anything since we have to now wait while we go up five floors...). Or you are waiting to make a left turn off a side road, but the people blocking you from making that turn are all backed up from a red light. (Hello, just because you can't go anywhere doesn't mean you needed to creep ahead blocking my path). Or better yet the highway you take home after work is backed up for miles because of an accident, so instead of merging and sitting in traffic, someone has to drive past the end of their acceleration ramp and cut ahead (Hello, being three cars further ahead doesn't get you home any sooner, oh, excuse me it gets you home 0.3 seconds sooner...)
I can understand being competitive/aggresive for something significant, like when you only have 1 item, the grocery store is packed, they just opened another register and the lady pulling two full carts is making a beeline, or when you have the chance to grab a foul ball, but not when it does no one any good (is there a ribbon for First on the Elevator that I don't know about?) or when it actively hinders others without benefiting yourself.
Have some consideration people and please bother to think while you are driving.