WASHINGTON: Billionaire Elon Musk bade farewell to Donald Trump in an extraordinary Oval Office appearance Friday, sporting a black eye, brushing aside drug abuse claims and vowing to stay a 鈥渇riend and adviser鈥� to the US president.

As the world鈥檚 richest person bowed out of his role as Trump鈥檚 cost-cutter-in-chief, the Republican hailed Musk鈥檚 鈥渋ncredible service鈥� and handed him a golden key to the White House.

But Trump insisted that Musk was 鈥渞eally not leaving鈥� after a turbulent four months in which his Department of Government Efficiency (DOGE) cut tens of thousands of jobs, shuttered whole agencies and slashed foreign aid.

鈥淗e鈥檚 going to be back and forth,鈥� said Trump, showering praise on the tech tycoon for what he called the 鈥渕ost sweeping and consequential government reform program in generations.鈥�

South-African born Musk, wearing a black T-shirt with the word 鈥淒ogefather鈥� in white lettering and a black DOGE baseball cap, said many of the $1 trillion savings he promised would take time to bear fruit.

鈥淚 look forward to continuing to be a friend and adviser to the president,鈥� he said.

But many people were more interested in the livid black bruise around Musk鈥檚 right eye.

Speculation about the cause was further fueled by accusations in the New York Times Friday that Musk used so much of the drug ketamine on the 2024 campaign trail that he developed bladder problems.

鈥楪o ahead punch me in the face鈥�

The SpaceX and Tesla magnate said that his son was to blame for the injury.

鈥淚 was just horsing around with lil鈥� X, and I said, 鈥榞o ahead punch me in the face,鈥欌€� 53-year-old Musk said. 鈥淎nd he did. Turns out even a five-year-old punching you in the face actually is...鈥� he added, before tailing off.

Musk, however, dodged a question about the drug allegations.

The New York Times said Musk, the biggest donor to Trump鈥檚 2024 election campaign, also took ecstasy and psychoactive mushrooms and traveled with a pill box last year.

Musk, who has long railed against the news media and championed his X social media platform as an alternative, took aim at the paper instead.

鈥淚s that the same publication that got a Pulitzer Prize for false reporting on the Russiagate?鈥� said Musk, referring to claims that Trump鈥檚 2016 election campaign colluded with Moscow.

鈥淟et鈥檚 move on. Okay. Next question.鈥�

Later in the day, when a reporter asked Trump if he was 鈥渁ware of Elon Musk鈥檚 regular drug use,鈥� Trump simply responded: 鈥淚 wasn鈥檛.鈥�

鈥淚 think Elon is a fantastic guy,鈥� he added.

The White House had earlier played down the report.

鈥淭he drugs that we鈥檙e concerned about are the drugs running across the southern border鈥� from Mexico, said Trump鈥檚 Deputy Chief of Staff Stephen Miller, whose wife works for Musk.

Musk has previously admitted to taking ketamine, saying he was prescribed it to treat a 鈥渘egative frame of mind鈥� and suggesting his use of drugs benefited his work.

Leaving under a cloud

The latest in a series of made-for-TV Oval Office events was aimed at putting a positive spin on Musk鈥檚 departure.

Musk is leaving Trump鈥檚 administration under a cloud, after admitting disillusionment with his role and criticizing the Republican president鈥檚 spending plans.

It was a far cry from his first few weeks as Trump鈥檚 chainsaw-brandishing sidekick.

At one time Musk was almost inseparable from Trump, glued to his side on Air Force One, Marine One, in the White House and at Trump鈥檚 Mar-a-Lago resort in Florida.

The right-wing magnate鈥檚 DOGE led an ideologically-driven rampage through the federal government, with its young 鈥渢ech bros鈥� slashing tens of thousands of jobs.

But DOGE鈥檚 achievements fell far short of Musk鈥檚 original goal of saving $2 trillion dollars.

The White House says DOGE has made $170 billion in savings so far. The independent 鈥淒oge Tracker鈥� site has counted just $12 billion while the Atlantic magazine put it far lower, at $2 billion.

Musk鈥檚 鈥渕ove fast and break things鈥� mantra was also at odds with some of his cabinet colleagues, and he said earlier this week that he was 鈥渄isappointed鈥� in Trump鈥檚 planned mega tax and spending bill as it undermined DOGE鈥檚 cuts.

Musk鈥檚 companies, meanwhile, have suffered.

Tesla shareholders called for him to return to work as sales slumped and protests targeted the electric vehicle maker, while SpaceX had a series of fiery rocket failures.