The most frustrating was perhaps in a mercenary-RP when another merc was just my character but genderswapped, and doing more-or-less the exact same thing but in the form of one-line posts that somehow tried to one-up/+1 my character in a casual RP.
Pretty much everybody unanimously agreed to put a bullet in their head when the third rescue-chopper arrived, my character got field-promoted.
A case of "It's not what you did, but how your did it after the consequences of such actions were already laid out and you deciding to double down on this other character's mistakes to the point of single-handedly nearly causing the mission to fail."
Another copy-pasted Allucard from Hellsing, and not even the funny abridged version. And they expected to get paid for it. Eneded up ramming a news-helicopter into him and dragging him into a river of Flouride-dioxide he had smuggled in himself by using their immortality as an infinite-funding glitch to bypass common-sense safety regulations... all just to get them to stop monolouging for five secends.
He survived that, of course, he ended up dying by getting a case of the zoomies in the woods and dropping a tree on himself in the epilouge. Again, they wanted to get paid for this, and they believed their posts were inherently superior due to being attributed a monetary value.