Tough to say. From the answers, it sounds like people are responding to a few different holds. There's a lot of triangles that I've heard referred to as the "reverse triangle." There's the one when you're in side control on top and have the head and near arm triangled. Also can happen off your back a lot. Kimura is your go-to move in that case. If on bottom, you might also try to sweep. There's also the reverse triangle from the back, and you can end up on top of him with his head sort of in your lap, and a triangle. If your legs are triangled to one side, you can go for an armbar. Or you can try to finish the choke by scooting your hips back to tighten, then grabbing his leg and pulling it all together.
So basically it all depends on which one we're talking about.