"TRIBAL KNOWLEDGE" (noun): That thing you should have done, if only someone had told you.
As a former NOC engineer, I clearly remember my onboarding, and especially the deep-rooted fear I felt every time I encountered an alert that was new to me – particularly during a night shift. My only consolation was that I was never alone during training, so there was always someone I could ask that very awkward question: “I’m new here, what do we do with this…?”