Triangulation is something we all do frequently, and I don't want to do it any more. To understand it, imagine a triangle with three points, A, B and C.
Person A wants to establish a relationship with person B. The easiest and quickest way to do this is to insult or insinuate person C, whom they both know. A and B find that their immediate link is through their dislike of person C. It doesn't just stop there, though. It's equally easy for B to find a connection with C by dissing A, and so the triangle goes on.
If we think about it, we do this ALL the time. It's so easy to put down others, without even thinking about it. I am trying to make myself aware of when I do it, and find other ways to connect with people.