While on Thursday's Conan, the 45-year-old Patriots Day actor revealed that Bieber had his underwear ads sent over to him. "I was like, 'You don't send a guy pictures like this, in your underwear,'" Wahlberg quipped. "He was proud. It was a big deal for him to do it."
However, the father of four -- who modeled for Calvin Klein in 1992 -- is at a different stage in his life than the 22-year-old pop star. "I'm trying to move away from that image," he admitted. "People give [Bieber] flack for kind of growing up in the spotlight and they say he has a bit of an attitude, but you look at the look on my face. I mean, I was the biggest punk in the world."
"I can say I've done worse things, but, yeah, that's not one of my proudest moments," he added.
Wahlberg had nothing but good things to say about Bieber. "He's a very nice young man. He's a friend of mine. I've spent time with him," he insisted. "He's very nice, young and polite compared to what I was."
The "Baby" singer headed straight to the salon for a new makeover ... this time going blonde! (Instagram)
Canadian pop megastar Justin Bieber (C) plays basketball with a young survivor of Super Typhoon Haiyan in Palo, Leyte province on December 10, 2013. Pop megastar Justin Bieber sang to and played basketball with young survivors of the Philippines' deadliest typhoon on December 10 after he flew into the disaster zone to boost an international relief effort. AFP PHOTO (Photo credit should read STR/AFP/Getty Images)
LOS ANGELES, CA - AUGUST 23: Justin Bieber attends a VMA Pre-Party hosted by Chris Brown & Pia Mia featuring Bera on August 23, 2014 in Los Angeles, California. (Photo by Araya Diaz/Getty Images)
LOS ANGELES, CA - JULY 27: Make A Wish recipient Wish Child Grace (R) and honoree Justin Bieber speak onstage at the 2014 Young Hollywood Awards brought to you by Samsung Galaxy at The Wiltern on July 27, 2014 in Los Angeles, California. The Young Hollywood Awards will air on Monday, July 28 8/7c on The CW. (Photo by Alberto E. Rodriguez/Getty Images for Variety)
LOS ANGELES, CA - JULY 27: The winner of Champ of Charity singer Justin Bieber (L) and singer Cody Simpson onstage at the 2014 Young Hollywood Awards brought to you by Samsung Galaxy at The Wiltern on July 27, 2014 in Los Angeles, California. The Young Hollywood Awards will air on Monday, July 28 8/7c on The CW. (Photo by Frederick M. Brown/Getty Images for Variety)
Justin Bieber attends the Yves Saint Laurent men's fall line and the first part of its women's collection fashion show at the Paladium, in Hollywood, California, February 10, 2016. / AFP / ROBYN BECK (Photo credit should read ROBYN BECK/AFP/Getty Images)