Voyeurism is a strange type of behavior in which someone gets turned on by watching other people, especially in sexual situations.
There are a lot of odd people in the world, including those who have an extreme, often sexual interest in watching other people — who may or may not be having sex. These voyeurs get off more on watching than doing. Some people might volunteer to be watched, but other times voyeurism involves someone watching another person without their knowledge. This is illegal and very creepy.