A thumbnail betrayal occurs on social networking sites such as facebook (the application 'are you interested' for example) when a male or female look really hot in their display picture, so u click thinking 'hell yea this is sweet' only to find out that they must have used some sort of magic 'grotesque removing' camera to take that picture with because they are, in fact, like a pile of shit which has been puked on. . attached to a bean bag chair. . with hair. .
dude: sweet this girl is hot *clicks*
dude 2: yea she looks sweet, look at her other photos
dude: omg ewwwww that was a pure thumbnail betrayal!! *gips*