The kind of thing you most definetly
do not want to
encounter whilst
driving.
Increasingly being installed where three or more roads converge, and traffic lights would be impractical. The idea is that you yield to traffic already on the roundabout; those to your right have priority.
But the problem arises when you want to take the last exit from the roundabout, in which case you're suppoed to move right in, next to the island, and then move back out when you reach your exit.
It really doesn't help when you stall at the entrance to one, either. (I tend to do that repeatedly).