President Donald Trump's "first buddy," Elon Musk, was seemingly everywhere in D.C. on Inauguration Day. Where (and with whom) was the billionaire?

Grimes, Elon Musk's ex, has responded to the backlash of his controversial hand gesture, which is going viral. On Monday, the Tesla CEO took the stage in Washington, DC's Capital One Arena, beginning his speech by saying, "Thank you for making it happen. Thank you," followed by slapping his right hand on his chest and extending it in salute.