Credit: Bloomberg via Getty Images Former Treasury Secretaries Henry Paulson (left) and Robert Rubin have a good laugh about income inequality.

Three of the world's richest and most powerful people (and Timothy Geithner) had a good laugh over income inequality earlier this year.

Former Treasury Secretaries Robert Rubin, Henry Paulson and Geithner were asked about the issue by Facebook executive Sheryl Sandberg during a conference in Beverly Hills. When Paulson responded that he'd been working on income inequality since his days at Goldman Sachs, Geithner quipped, "In which direction?"

"You were increasing it!" cracked Rubin, as everyone on stage roared with laughter.

Watch the exchange:

The April conference was hosted by former junk-bond kingpin Michael Milken, who served prison time in the 1990s for securities and tax scams. Milken has since attempted to rehabilitate his image through philanthropy.

After serving as Treasury secretary under President Bill Clinton, Rubin made over $120 million working at Citigroup, which he left shortly before the faltering megabank was bailed out by taxpayers. Rubin spent 26 years at Goldman Sachs, and ran the firm for his final two before joining the Treasury.

Paulson made about $500 million working at Goldman before serving as Treasury secretary under President George W. Bush.

Geithner, sadly, had to settle for making $411,200 a year when he served as president of the Federal Reserve Bank of New York. Geithner and Paulson coordinated the bailouts that saved Citi and other banks in 2008. Geithner succeeded Paulson as Treasury secretary under President Barack Obama and took a high-paying job at the private equity firm Warburg Pincus in 2013.

Sandberg, whose question prompted the moment of levity, is worth almost $1.2 billion. She worked for Treasury Secretary Larry Summers during the Clinton years and has been a staunch advocate for women's equality in the workplace.

While in office, all three men advocated Wall Street-friendly policies that helped bolster pay for top bankers. Overall worker wages have been stagnant for decades and falling for most workers since 2007.

Hilarious!