This is something that just happened to me and it really annoys me.
I'm trying to cross a road, there's a car on the right that's going the right speed, I just need to let him go or I can actually cross before he gets to me, but then, there's another moron on the left, usually a old person, who is driving just slow enough for me to have to wait for him to go but that by the time he gets here, I will have to wait for the car on the right too.
Can't really explain it but basically if the car on the left was driving at correct speed, I would just wait for him to go and then cross but because of him I have to keep waiting for god knows how long until I get another opportunity. Really annoys the hell out of me and I wish I could open their door and punch them in the face Grand Theft Auto style.