London’s Channel 4 News reporter Krishnan Guru-Murthy learned something that fans of the upcoming “Avengers: Age of Ultron” already know: don’t trifle with Iron Man.

Robert Downey Jr., in town to promote the next Marvel blockbuster, walked out of an extremely cringe-worthy interview with Guru-Murthy when the interviewer went off script with questions about his history with drugs, drinking and his time in prison.

Things started out innocently enough. Guru-Murthy asked relevant questions about Downey Jr.’s take on his roles in “Iron Man” versus “Avengers,” which the star took in stride, diligently answering with thoughtful responses.

The session turned sour, though, when Guru-Murthy inquired if he could ask "personal questions."

Obviously annoyed, Downey, Jr. looked to someone off camera, as if to say "end this now."

"You have as much time as anyone else has," he said.

Guru-Murthy then asked about Downey, Jr.'s relationship with his father and that, as they say, was the straw that broke the camel's back.

"I'm sorry, I really don't .. what are we doing?" Downey, Jr. asked before standing up and exiting stage right.

Guru-Murthy looked befuddled, but he's no stranger to awkward interviews. He had a similar testy situation with Quentin Tarantino who, while promoting "Django Unchained," lost his cool and berated Guru-Murthy.

"I'm shutting your butt down," he told the reporter back in 2013.