I have not seen this recently, but I used to see it a lot....

A person who signals just becuase the person in front of them - signals. Its like telling people behind them - the person in front is signalling! Very frustrating.

Imagine sitting at an intersection when 2 cars are coming from the left. The first person signals the turn, then the second car signals becuase the first one does. You think they are both going to turn, so you start to ease out into the highway. But luckily you don't becuase the second driver does not turn!