at a previous workplace, every new hire would discover the handwritten bubblesort in our codebase, freak out, and submit a pull request to fix it.

and every new hire got taken to the whiteboard to learn about sort algorithm performance: bubblesort is O(n) in the best case.

and in our codebase, the data being sorted fit that best case (the data was already sorted or almost sorted).

Not only in best case. Haven't seen this elsewhere, and know only few people who know that, so, a kind of a puzzle: what are the conditions when bubblesort is always O(n)?