A person (male or female) who intentionally or unintentionally stops the progress of two others getting their game on.
The dude and some fine-ass woman were gettin' their game on when KGB showed up fucked up and put his arms around them. He didn't even know he was being a cock blocker
Actively cock blocking your wingman with the force of a 20 ton nuclear bomb. Not to be mistaken for regular cock blocking which is done passive aggressively. This form of cock blockage is done so effectively that you will never again see even a remote patch of feminine pubic hair in the presence of said cock blocker. Sometimes going as far to not get laid him self just so you don't get laid.
An insecure asshole who does not have the balls to open a conversation with a woman, but will not hesitate to butt into any interaction already in progress. They will then proceed in destroying any chance of a hook-up. Most times, what they refer to as "their game" is so poor that not only do they fuck up YOUR prospects they end up scaring away the "prey" to another table or "Lance Goodthrust" at the other end of the bar. They are the most effective birth control device known to mankind. Stay away from these people or become a monk where you'll have just as much opportunity for getting some pussy.
You're talking to a hottie that you've managed to cut away from her heard. You're just about to "close the deal" with a number or invite to a more secluded place ie. your car, when "CB" shows up and hangs over you both like a plague from God or bad breath or herpes. The conversation, which had been flowing with magical bullshit, becomes strained and uncomfortable. She mentions that "it's getting late" as she eyes the safety of the heard. Her departure is followed by, "She was a bitch anyway!" from the asshole who's just ruined it for you. You supress the urge to punch him in the liver, move to another part of the bar where you start again in the hopes that he cannot find you. For surely he is the Devil.
Paul is a total cock blocker. That guy is like a giant cock blocking robot developed in a secret fucking government lab. I was about to hook up with Lily and he ruined all my hard work.
Sonny: So did you get with Linda at the party?
Mike: Nah bro, Sam, Dan kept interupting on purpose, and Dustin was cock blocking, it was a freaking cock blockade, I couldn't get through.