Joshua Achiam, OpenAI's chief futurist, testified in the Musk v. Altman trial. Bloomberg/Getty Images OpenAI exec Joshua Achiam testified about a "tense exchange" he had with Elon Musk in 2018. Musk, Achiam told the jury in the Musk v. Altman trial, called him a "jackass." The two clashed over AI safety, and Achiam's colleagues later gifted him a gold "jackass" trophy. An OpenAI executive told a federal jury Wednesday how Elon Musk once called him a "jackass" during a heated clash over AI safety. Joshua Achiam, OpenAI's chief futurist, recalled the "pretty tense exchange" during testimony in the California civil trial between Musk and OpenAI CEO Sam Altman . "He snapped and called me a jackass," Achiam testified. Achiam said that around 50 to 60 employees had gathered during a February 2018 company all-hands meeting for a question-and-answer session ahead of Musk's planned departure from the startup he cofounded with Altman.…