White Knighting typically occurs when their are two men and one girl. White Knighting is easy to spot and very annoying when you are trying to get laid with a crappy wingman.
White Knighting is when one man is trying to get a girl into his bed while in the same area as his friend, his friend (if he is a White Knight) will typically attempt to disperse the conversation by presenting his chivalrous words such as: "Have some respect for women, Johnny" or "Miss, he's just trying to get laid" while simultaneously attempting to get laid himself by showing respect to the women. A White Knight will never act chivalrous when he is not around another guy.
Jim: Hey babe, you wanna go back to my place? I'll make you some food.
Lancelot: Jim, your just trying to sleep with her, I see this every time we go out
Girl: Excuse me? I'm not a slut. (leaves)
Jim: What the hell Lancelot, quit your White Knighting, I was about to get laid.
Lancelot: Dude I know! We should totally go out again tomorrow! I'm about to get that girls number, she's totally into me.