Pet peeve – something which you hate, which is unique to you. In other words, nobody else hates this particular thing – at least, they don’t hate it as much as you hate it. It is a unique thing about you – there is this one thing that completely annoys you.
For instance – “His pet peeve was people who shake hands for too long. A short handshake was okay, but if the person kept on gripping, he would suddenly feel uncontrollable rage, like he wanted to slap them”