I'm not sure why everyone's downvoting you rather than explaining -- it took me a couple of rereads to understand this part of the story too. Nobody was switching at the gate, they were doing it on the plane as usual. The reason the gate is mentioned is that this flight was leaving from gate C3, but OP misread their boarding pass and thought that C3 was their seat. So that's the one they originally mistakenly gave up, rather than their real seat.
Orchidlance t1_ja4zh96 wrote
Reply to comment by do0tz in TIFU by giving away a seat that wasn’t mine. by tomfoolery77
I'm not sure why everyone's downvoting you rather than explaining -- it took me a couple of rereads to understand this part of the story too. Nobody was switching at the gate, they were doing it on the plane as usual. The reason the gate is mentioned is that this flight was leaving from gate C3, but OP misread their boarding pass and thought that C3 was their seat. So that's the one they originally mistakenly gave up, rather than their real seat.