At work, the boss wanted me to improve the performance. Refactored the whole code, no luck, it just made it worse. Reverted back the code, got curious over a single line, changed it. And it solved everything.
Expectation: Working on boss battle.
Reality: "Look at how awful are these code and database organization. Let me clean this mess", *yet, casually adding more modules that I have no idea if I would use it later*