Talk about bad table manners.

Hedge fund billionaire Bill Ackman got into a testy exchange with Joe Biden at a private dinner in Las Vegas last month, making a snarky comment after the former US vice president spoke about the tragic death of his son.

The testy altercation began after Biden answered a question by former Florida Gov. Jeb Bush about why he didn’t run for president, Fox Business Network first reported, citing sources.

The former VP grew emotional as he explained he bowed out partly because of his son Beau Biden’s death from brain cancer in 2015.

“I’m sorry … I’ve said enough,” Biden said as the room grew quiet.

“Why? That’s never stopped you before,” Ackman then called out, according to a blow-by-blow account of the exchange by Fox Business.

“Who is this a—hole,” Biden reportedly asked a seatmate, unimpressed by the hedgie.

“Look, I don’t know who you are, wiseass, but never disrespect the memory of my dead son!” Biden told Ackman.

The hedgie attempted an apology but was told by Biden to “just shut the hell up.”

A source told The Post the dinner had already gotten off to a tense start as another attendee pressed Biden on policy issues at what was supposed to be a lighthearted affair.

A spokesperson for Pershing Square quibbled over parts of the altercation and said, “Bill had a great time at the dinner and enjoyed spending time with the former vice president.”

Other attendees at the VIP affair included financiers Jon Corzine, Dan Loeb and Steve Cohen, as well as comedian Steve Harvey and Valerie Jarrett, a former aide to President Obama.

Anthony Scaramucci, founder of SkyBridge Capital, hosted the ill-fated, May 18 dinner at the fund-of-funds’ annual SkyBridge Alternatives (SALT) conference.

Incidentally, SkyBridge Capital’s flagship fund saw net outflows of $1.6 billion for its fiscal year ending March 31, leaving the fund with $5.4 billion in assets, according to a filing with the Securities and Exchange Commission earlier this month.

Skybridge did not respond to requests to comment.

Scaramucci, an ardent Trump supporter and fundraiser, sold Skybridge to a team of foreign buyers earlier this year in anticipation of landing a gig with the Trump administration.

The deal is expected to close this summer although Scaramucci’s White House ambitions have been delayed.