What's the worst example of not "reading the room" you ever witnesses?

I worked a night shift at a lobby of some residential building, with another guy patrolling the building.

Some mentally unstable person wound up sitting at the lobby while the guy was on patrol (long story), so I sent him a message explaining the situation as I didn’t want to talk about it in front of the person.

The patrol guy comes back, looks at the person, looks at me and says “so, who’s the psycho?”