One time I was in an argument about whether something could be done within a six month timeframe, and when a manager dropped in and asked a few clarifying questions it became clear that the other guy was working from the underlying opinion that nobody cared at all about the deadline and they were really just arguing about whether they wanted to do it. The timeline was clearly literally impossible, but he did want to do it.

Ended up that he told manager we could do it, manager was nuts and so signed us up, I left the team, they missed it by about two years. But he had fun, apparently.