In forum parlance, it means rushing to the aid of another poster for whatever reason. An accusation typically reserved for when a poster is being hammered by another poster(s) and the accused leaps in to defend them, usually without thinking things through as to why the person is being attacked.
Poster A: <Says something unfunny>
Poster B: Shut up, douche.
White Knight: Hey, leave him alone. Why are you all ganging up on him?
Poster B: Quite white knighting, douche.
by Boojoorooroo December 4, 2007
Get the white knighting mug.
When a male, preferably after sex, stands before a kneeling female, whom he preferably just had sex with, and cums on both of her shoulders before declaring her a "knight of the white table." The more cum used, the better.
Male: "Yeah, I brought her back, fucked her, then white knighted her."
Friend: "Ah, always great to see a new addition to the white table. White knighting for the win!"
by Matty Moran the Man February 28, 2012
Get the white knighting mug.
when a man shoots his warm load over your shoulders

Also;

When a man comes to a girls rescue on the internet even when she's wrong
Bob: "Did you hear about that guy who thirstily stood up for girls on the internet?"
Saget: "Yeah, I heard he was caught white knighting those same girls before in real life!"
by Credible Quinn September 20, 2019
Get the white knighting mug.
1) A man who stands up for a womens right to be an absolute equal, but then steps up like a white knight to rescue her any time that equality becomes a burden.

2) A man who Promotes gender equality but practices special privilege for women.
When a woman believes she can do absolutely everything a man can do and better, but when she is asked to list something heavy as her everyday chore the white knight will come to defend her when she protests.
by DigitalAcolyte February 25, 2014
Get the White Knight mug.
A white knight is a man who will go to great lengths to defend women, whether they are attacked physically, verbally, or sexually. In fact, it does not matter if the woman is attacked at all. They will ditch their own best friends, hit people, or say things they never would elsewhere, just to "protect" that woman. White knights come in all shapes and sizes.

White knights are generally men with seriously low self esteem issues. They are also sexually depraved, and have never had a girlfriend or any female attention for that matter. They use their white knightry as a last ditch attempt to get laid and/or "prove" their worth to society. Usually socially awkward people who tend to live in fantasy worlds, and will brag about their "heroic deeds" and "manliness" in every conversation with people. Tend to identify as women supporters or feminists, but could not be further from the truth as all they do is reinforce the idea that women are weak.

Hated by true feminists and men's rights activists (MRAs) alike.
Examples of white knights:
1. A guy and a girl are walking in a mall. They start to argue, and the guy suddenly grabs the girl's hand.
"Let go!" The girl yells.
Suddenly, a random stranger appears out of nowhere.
Stranger: "You coward! How dare you touch a woman! Don't you know hitting women is cowardly and unmanly?"
*punches guy*
*guy retaliates, beats the shit out of stranger*
Girl (slaps stranger): "Idiot! He's my boyfriend. Why don't you go mind your own fucking business?"
*girl and guy walk out*

2. A bar
John yells at a girl: "How dare you cheat on me? Fuck you, you bloody whore! Bitch!"
A random guy comes in
Random guy: "How dare you use such words for my beauty? Take that." (Beats John up)
Girl: " Aw, how romantic!"

(To another guy) "Come on honey, let's go!" (Both walk away)
John: "man, get a life. These sluts don't give a shit about you."

3. Chris: "Come on Paul, you know me and Thomas were never there at the party. Caroline is lying."
Paul: "No, shut up. I know you liars. My sweet Caroline cannot lie."
(To Caroline): "Don't listen to these women hating scumbags. I know you are always right."
Caroline: aww!
Thomas (to Chris): "man, Paul is such a loser and a white knight."
by dfvnk October 1, 2018
Get the White knight mug.
Usually a man who puts himself in someone else’s business to stick up for a girl, even if she’s wrong or has done something wrong. White Knights usually do this for some sort of reward, nudes, sex, or something along those lines.
Guy: You’re such a whore!
Girl: No I’m not!
White Knight: EXCUSE ME SIR DID YOU JUST CALL THIS WOMAN A WHORE? YOU SHOULD BE CALLING YOUR MOTHER A WHORE INSTEAD!
by DMHStudios12 November 15, 2018
Get the White Knight mug.
A person with low self esteem who combats this with a unwavering need to aid others who may or may not need it. They usually have very isolated personal lives as they are very judgmental of others, surrounding themselves only with those who feed their desire to help and feel as a savior. Most commonly sighted in young men in regards to women, this is only a lesser form as it is usually only temporary, fading with life experience. More serious cases occur in correlation with chronic self esteem problems where the person needs to maintain a high view of themselves through self righteous acts of kindness. These people enjoy surrounding themselves with troubled individuals, who form a farm which is harvested for what they use as pseudo self esteem.
Don't give the white knight reason to flaunt his "good deeds".
by RedShiftXIII March 14, 2015
Get the White Knight mug.