The technique below, dubbed the "ladder-up armbar" by Guerilla Jiu Jitsu founder/coach David Camarillo, is solid meat n' potatoes Jiu Jitsu. It's basically his precise take on a proper armbar you get from the guard when your opponent stands up and thinks he's going to pass you. Instead, he gets armlocked and you get high-fives. We love this kind of Jiu Jitsu.
In a world of crazy, over-stylized, inversion-based, new-school technique, this ain't that. Instead, it's tried and true, simple in some ways, but extremely precise, sophisticated and technical throughout. The truth is, achieving a proper armbar from your guard against a legit, well trained and equally game opponent ... is very difficult. And, that's because that kind of armbar is one item on a very short list that most grapplers are taught to defend early on. That just means your technique - namely your timing, muscle memory and precision need to be spot on. Camarillo is an excellent coach in this technique. But, like most good techniques, you have to do the hard work of countless drilling and attempting in play.