This one seems obscure at first, but is really very accessible… and very powerful. It can change your life, all by itself.

The three objects are friends, enemies and neutrals…

The three poisons are craving, aggression, ignorance (which are  sometimes rendered as: passion/anger/delusion, or attachment/aversion/indifference).

The three virtues are the wisdom sides of the three poisons – i.e., ‘the flip side’! What this means is, the wisdom you gain from observing carefully when you experience the three poisons. On one level, this is the post-meditation/everyday life version of tonglen, and can be practiced fully only when tonglen is understood. Basically this amounts to uncoupling from the objects of your emotions and attachments and realizing that without the objects, the passions have no power… Trungpa:

The practice of this slogan is to take the passion, aggression, and delusion of others upon ourselves so that they may be free and undefiled… Whenever any of the three poisons happens in your life, you should do the sending and taking practice… If you have no object of aggression, you cannot hold your own aggression purely by yourself…. you can cut the root of the three poisons by dealing with others rather than by dealing with yourself.

But the simple, straightforward level, the accessible version of this is to realize that whatever bad experiences you are in at this moment can teach you what suffering is for others and thus help you develop understanding, insight or wisdom (panna) — and thus compassion for others.

A simple personal example: I was driving to work a few days ago in a very stressed state due to a combination of circumstances too complicated and mundane to go into, but suffice it to say I was so stressed that I began to wonder if I was safe to drive. As I was driving along, I realized that many of the people around me on the road must be experiencing the same kinds of stress, and that indeed that stress could be the source of many of the frightening and annoying things that other drivers often do  – things that typically get an angry or at least contemptuous response from me. Seeing how this stress could be affecting others, I realized I was able to tap into a source of compassion for them which is helping me be less annoyed and much more equanimous in my daily drive.