Oh, OK. So what this guy did is he misread his ticket

The ticket says: Gate Number C3.

This is where the plane arrives, and where you board.

The plane ticket says: Seat Number: A7.

What he did was, he sat in seat C3, instead of A7, and when someone wanted to sit in his seat (C3) he gave it away and sat in their sear (G24). Someone else wanted to swap his new seat, G24, for their seat, F12. He sits in F12.

He notices a commotion around area C3, the original seat he sat in and gave away. Someone's boarded the plane, and tried to sit in their seat, C3. The person sat in it argues, no, I swapped my seat for this seat. This guy shows them his ticket, this is HIS seat!! The guy sat in C3 tries to locate the man he swapped with, but he's no longer in the seat he gave him! They finally locate him and point out that he's an idiot, he sat in the gate number, not his actual seat.

:)