Unlike most married couples, Ashton Kutcher and Mila Kunis have had two first kisses: one on television and one for real life.

Mila Kunis was still a minor when Ashton Kutcher first kissed her while filming That ’70s Show, he recounted on The Howard Stern Show on Wednesday, June 21.

He said that they had a brother-sister relationship: “I was 19, she was like 14. Yeah, I did her chemistry homework for her. I think I was her first kiss, like, on the show. We have our first kiss memorialized on a TV show!”

EVERETT

“It was really weird. I was like, ‘Isn’t this illegal? Like can I-am I allowed?'” he continued. “It was really awkward because I’m like a 19-year-old kid. She was 14! She was like my little sister. I wanted to make sure she was okay.”

Both Kutcher and Kunis claimed to have no interest to each other on That ’70s Show. When Howard Stern brought up Kunis’ denial from his interview with her the night before, he said, “She’s lying! She has, like, a journal or, like, a diary from when she was a kid where she wrote, ‘Oh, this guy’s hot.’ She thought I was cute!”

“At first I think she thought that I was good-looking,” he said. “Shortly thereafter, I was just annoying to her because I was like a big brother. It was like, ‘He’s annoying, because he’s always looking out for my best interest.”

Kutcher also revealed how their real-life romance began, which was essentially their rom-coms No Strings Attached (Kutcher) and Friends With Benefits (Kunis). He remarked, “We legitimately lived out our movies. It was weird and fast and—you know at the time it was honestly like okay, we’re going to be in this—we have an agreement around [our friends with benefits relationship].”

Mila Kunis and Ashton Kutcher attend a basketball game between the Oklahoma City Thunder and the Los Angeles Lakers at Staples Center on December 19, 2014 in Los Angeles, California. Noel Vasquez/GC Images

After Kutcher’s divorce from first wife Demi Moore, the former costars reunited, and it was all owing to cigarettes.

Kutcher admitted, “I think I was smoking cigarettes at the time, and I was still a smoker. And she had quit smoking and she was like, she wanted me to like shot gun a cigarette smoke so she could breathe it in and I was like, ‘All right.’ And I started doing this. And gradually through the night, it got closer and closer and closer.”

Fast forward to July 2015, Kutcher and Kunis married after a three-year relationship. The couple also has a 2-year-old daughter, Wyatt, and a 6-month-old boy, Dimitri.