voyer
A person who gains sexual pleasure by watching others have sexual intercourse.
Henry is a voyer cause he gets off by watching Erma have sex with other men
facebook voyer
Person on facebook that doesn't go online and never post comments or replies. Just looks at other people's posts.
I never see Johnny on facebook but he sure knows a lot about all my posts and my pictures. He's a facebook voyer so I will defriend him.