The former late night host made a surprise appearance during Martin Short and Steve Martin's A Very Stupid Conversation comedy tour

Credit: Mark Sagliocco/Filmmagic; John Paul Filo/CBS/Getty

David Letterman couldn’t just stand by and be silent when he heard billionaire Donald Trump is running for President.

The former host of The Late Show took a brief hiatus from retirement to roast the embattled candidate in a surprise appearance at Martin Short and Steve Martin‘s San Antonio, Texas A Very Stupid Conversation comedy tour stop.

Letterman told the Majestic Theatre audience on Friday that he was enjoying his new relaxing lifestyle until he heard about Trump’s 2016 bid.

“I’ve made the biggest mistake of my life ladies and gentleman,” he joked, before pulling out one of his iconic Top 10 lists from his suit.

The special list, which broke down some fun “facts” about the real estate tycoon, included several digs at Trump’s oft-ridiculed hair.

“No. 4: Trump would like all Americans to know that that thing on his head is free range,” said Letterman, before moving onto no. 3, “That’s not a hairdo, it’s a wind advisory.”

Fans Say Goodbye to David Letterman

Letterman, who joked that the appearance was his “first night in show business,” later posed for a selfie with Martin and Short.

“A big comedy night for Marty and me in San Antonio. Surprise guest, David Letterman,” Tweeted Martin, who was recently honored with the American Film Institute’s 43rd Life Achievement Award.

The actor later posted another photo of Letterman backstage, this time with Short dressed as a woman.

“Just another night backstage with Marty and Letterman,” he said.

Letterman stepped down from the Late Show in May, and will be replaced by Stephen Colbert in September.