Rancor Racks

Inspired by

Rancor Racks are an important tradition among the centaurs of the plains. Many of them are quite hot-headed, and to prevent their temper getting the best of them, the tradition of rancor racks has been adopted.
The large entrance halls of any centaur home has its wall decorated with shelves of various depths and distance to one another. Wooden sculptures called grievances are put on display there, indicating all the times that a resident of this hall has felt wronged by someone that hasn't been righted yet. The sculptures vary greatly in terms of size, attention to detail and care they received, and it is not always clear who put a grievance up for display until you see that person take care of it.
Houses with teenage kids tends to have a lot more grievances for display than households mainly consisting of adults.

Details

Whenever a centaur feels wronged, they will go and pick up a piece of wood that calls out to them in that moment. They will then proceed to carve it - not to represent anyone or anything in specific, though this does occasionally happen. The common practice is to focus on your rage and let it be the fuel that shapes the wood, without thinking about what you want to do. The first version of any grievance is almost always crude and awkwardly shaped.
Most grievances don't stay on the Rancor Rack for long, getting discarded either when the hurt centaur calmed down or the offender apologized. Some, however, remain there for longer, and during the months and years will be picked up time and again when the offended person remembers what happened. Often, they go back to working on it, this time more level-headed and coordinated, and these grievances will become more intricate and elaborate as time goes by. Shapes will be worked on to actually resemble things, and the wood will become smoothed and polished.
Sometimes this gets used as an allegory about how something bad can turn into something beautiful. A lot of the time, an old, well-maintained grievance becomes something of sentimental value that the Offended will use to kindly and playfully tease the offender. These grievances technically don't deserve a place on the Rancor Rack anymore, but particularly with old centaurs keeping them there is popular.
For good friends, at some point they will ask about the history of the well-maintained grievances, prepared for a good story. It is not uncommon, though, that one of their habits is a pet peeve of the owner of a house and this is the only way for them to learn of this.
For this reason, the tradition of the Rancor Rack and maintaining your grievances carefully is still going strong, despite some centaurs feeling that it encourages to harbor bitterness and ill will towards each other.

Abstract Bird by Los Angeles County Musem of Art

A well-maintained grievance

"He's gonna make a great carver one day."

This saying is popular among centaurs as a backhanded way of saying someone has quite a temper and difficulty giving up grudges, since it means he will most likely work with wood a lot. In a similar vein, calling someone a carver is also sometimes used as an insult.

Other traditions related to this is giving someone a piece of wood as a gift, meaning that you think they are in the wrong and if they don"t budge they can as well already start working on a grievance about you, because you sure as hell don't care.