The army does this by actually shooting at you.
My opinion on this matter isn't very popular around these parts, but I'll share it gladly: If you want to prepare for a real life situation, you need to experience a real life situation. If someone starts something with you, end it. If you don't want to do that because your kung-jitsu instructor is a man of peace or whatever, then the best thing you can do is to prevent a situation from escalating. The moment someone is up in your face and you know talking won't help (only experience can teach this, unfortunately), then you take immediate and decisive action. A straight or cross to the chin will knock out just about anyone who isn't much bigger than you are. My dad weighed 75kg and he knocked a guy out who weighed at least 100kg with a single well-placed kick. So there is quite a large bit of leeway when making the calculation.
Seriously: take the shot the first chance you get. The more talking and shoving going on, the more people in the crowd forming around you will get worked up, ergo more "escalation" and the bigger the chance that the situation will get out of control. Drop the other guy as soon as possible. This is the same strategy employed by nations on the brink of war: take out the other guy at the first sign that war is imminent. What happened when the USA attacked Iraq? Did they wait for Saddam Hussein to get his tanks into position, or did they tank-rush him and destroy his palace before he even finished his breakfast?
The other upside to this is that you can take him out before his buddies even know he's looking for trouble, saving you risk of getting a beat down. Fights always start out with two guys stepping outside and it's only when a few minutes have passed that someone announces it and attracts a crowd. Your goal is to knock him out and get out of there before the crowd shows up.
UPDATE: as I was saying, my opinion isn't very popular. See, this is where experience gainsays theory: cops will NOT arrest you if you didn't use a weapon. But if they do arrest you, you will be let go with a warning. And if you are charged, simply knocking someone out without causing major damage will net you a suspended sentence at worst, but usually nothing more than a "don't do it again". Taking the initiative allows you to minimise the damage dealt. If you pre-emptively take out your opponent, you might just need to land one punch. Conversely, in a full-on fight, you're going to have to strike targets as they become available, e.g. eyes, nose, mouth etc. Those bleed a lot. Clipping someone on the jaw leaves very little damage in comparison.
Thugs or not, my students performed exceptionally well not only in competition, but also in the real world. Only one of them ever had to "neutralise" an opponent before word got around that we actually know what we're doing and that we're not a turn-the-other-cheek school. After that, no one ever tried to goad us into a confrontation again. Thus preventing further bloodshed (or bruised ego's at any rate). If you're not prepared to back up the claim on your Tap Out shirt, you're just inviting more drama from drunk douchebags. It's called MARTIAL arts for a reason. Otherwise you could just as well take a course in diplomacy and proper tea ceremony etiquet.