lmao, like that Homer Simpson quote XD
I recommend getting a book by Geoff Thompson called The Art of Fighting Without Fighting. It'll teach you how to make yourself less of an easy target, teach you how to spot trouble, and avoid it. To compliment this, "The Three Second Fighter: The Sniper Option" will go well. Teaches you how to set a guy up and knock him out in one punch and get the hell out of there if you need to.
There is no one technique, to quote the first reply, especially in aikido, since aikido deals mainly defensively. I'd suggest if you wanna learn something quick, check out those books, and work on speed and accuracy for that one punch. Most fights are over once the first punch is landed, it doesn't take much else, so if you get the first punch in, you can scarper before the guy recovers.
I wish Geoff paid me to say that lol. But I think that'll help you. You can get The Art of Fighting Without Fighting from www.geoffthompson.com
as a free downloaded ebook. It's only a short book. I hope it helps you though.