At peak season every year, O’Leary says something crazy like they are going to charge for the bathroom, or charge fat people extra, or get rid of arm rests, or have standing room only. The tabloids run the story, and always mention how cheap the flights are, including whatever the cheapest deal at the moment is.
It’s very, very obvious advertising. The tabloids go along with it because it makes people angry, which drives traffic.
Although in both cases, it's hard to tell if they were serious, or just doing PR.