My killer PR:
I made a small feature and it was to be merged in my senior's branch.
So I made it, resolved all the conflicts and when it got merged it broke my senior's branch.
This is nothing new and it happens, so me and him sat down and got it working. After two days, his branch got merged and broke it's parent 😂, after investigation my code was the reason, got fixed and merged.
Same thing happened 3 more times, and every time my code was the culprit.
Now for staging we thoroughly tested everything and deployed it, after running for 2 hours the piece of shit broke again 😂😂😂.
A meeting was arranged for scolding the team, and after the meeting the architect comes to me and say "how did you manage to fuck things on so many levels, literally?". I handled it like a pro with an awkward laugh.

We exhaustively checked it for production. Deployed, it did not broke, we were happy. After a month of successful run, I just joked about the above incident while we were working on next release on morning coffee. That cursed thing broke on the same evening. I was like 😮