I think my husband has been guilty of DYKIA behaviour in the past. He is normally very polite but does have a territorial obsession. On boarding a full 777 in Bangkok some years ago ( the aircraft where the middle rows have no overhead locker) a gentleman put his hand luggage in our overhead bin. I had not yet boarded anD my husband told said gentleman he couldn’t put his bag in our overhead locker as his wife needed to put hers in it ( wife being me). He politely pointed out that there was no overhead locker above his seat but my husband would have none of it. He did manage to find a space somewhere else. All well about to get settled in for takeoff when cc announced ‘we are pleased to announce we have one of our longest serving pilots in our cabin. Guess who he was? My husband ( who has the utmost respect for officers) turned red and has to this day never repeated his rant! A real DYKIA