We knew Elon Musk's lawsuit against OpenAI's co-founders would cause fireworks when it came to trial . When Sam Altman took the stand, as the OpenAI CEO did Tuesday at the federal courthouse in Oakland, California, we knew he'd face allegations of being less than truthful. We didn't know, however, that Altman would deploy a memory of Elon Musk showing off his favorite memes, to surprisingly strategic effect. Or that a "crossed fingers" emoji would gain new meaning. Or, in probably the most dramatic moment of the trial, Altman would be confronted over whether he lied to the Senate when he said he had no financial stake in OpenAI. Here are the four most memorable claims in a most consequential day in court: 1. Musk 'demotivated' OpenAI — and wanted it for himself Altman first faced friendly questioning from OpenAI's lawyers, which allowed him to present his side of the narrative.…