Headcanon that orcish society weirdly complex. More headcanon incoming below
The core principle of their society is Victory at any cost, no matter what. It doesn’t matter if its in combat, a contest, or even something as simple as a simple recreational game. However, because of this notion that your personal victory is all that matters, orcs have developed a societal, extreme level of poor sportsmanship and being absolutely horrendous in defeat. If you lose, it wasn’t because the other person was better, first or even lucky. It must be because they cheated, they were dishonorable! Their victory no longer counts and your families are now in a generational blood-feud.
This assumption that everyone else cheats, combined with that you must achieve victory at any cost despite this, has given rise to a society in which EVERBODY uses all matter of nefarious means and skulduggery to achieve success, all while pretending not to and calling out everyone else. Sabotage, spreading nasty rumors, poisoning, assassinations etc. Whatever can be used to give an edge, no matter how insidious, an orc will always take it. Because they naturally assume their enemy does as well.
So we have a society built on a strange almost performance, in which everyone talks and boast about their honor and how everyone else is untrustworthy. All while they are all doing exactly the same thing in the shadows. For a tribal society which on the outside looks fairly simplistic, there is a strange complexity to them due to this odd song and dance of betrayal and keeping up appearances.
Edit: Further headcanon. This is also why we have seen so many examples of orcs being so brutal towards their defeated foes, often committing torture and humiliation rather than a simple kill. In their minds, their foes have been just as insidious, more so actually, than they have been. So now that they are defeated, a quick death or graceful defeat is not an option. They must be punished for their dishonorable ways, in the most painful and humiliating ways imaginable.
And just like before, it doesn’t matter what this is or who their opponent is. It could be a battlefield duel, an innocent civilian, a child. Even animals. It could be something as simple as a children’s game or just reaching a line at the vendor stall faster than you. Your foe is wrong, dishonest and must be treated with utmost hostility and you must be as awful as possible when you “win” to show that you are better.