A term used by retards on internet forums to describe somebody who gives a compliment to a female user. Said retards typically make huge leaps of assumption and often think of the person posting the compliment is a white male, lonely, and under the guise that posting compliments anonymously on the internet will somehow make the girl love them or have sex with them out of gratitude.
A) "Hey, you look really pretty."
B) "I fucking hate white knights like you. These girls aren't going to have sex with you. Try leaving your basement once in a while, creep."
A) "I'm a female, and all I did was say she looks pretty. What's your problem?"
B) "Urrr... HURR DURR Sorry I thought you was a guy and it's not okay for guys to give compliments derpderpderp."