What's the worst example of "not reading the room properly" have you seen?

Trump making that "Pocahontas" snipe about Elizabeth Warren—at a ceremony honoring Native American veterans. They looked at him like they thought he’d lost his
mind. 😳

A guy told me the end of the line was behind him. It was the third time -. I'm just waiting..I said "Oh, you're right, everyone must be before me!". He said"Shut up- it's alright to cut in front of you, you're okay.". I said, stupidly,"No, it's not okay,the line is just as long as in the Soviet Union in 1989, but we're paying a whole lot and working away our lives, here..." Guns came out. "Politics? No politics, lady.". ... I was still thinking of chattering some more... Two more guns came out.....
Great Fred Meyer. Open minded America.

Trump praising Putin's invasion of Ukraine takes some beating. Staggering ignorance, even by Trump's own standards.

Not personally seen but read about: Michael Richards (Kramer from TV's "Seinfeld") exploded in anger as he performed at a famous L.A. comedy club about 16 years ago, hurling racial epithets at a heckler, that left the crowd gasping. It essentially ruined his career.