Little did they know they’d get married! Ashton Kutcher recalled on The Howard Stern Show on Wednesday, June 21, that when he first kissed Mila Kunis while filming That ‘70s Show, she was still a minor.

“We’ve known each other for 20 years. I was 19, she was like 14. I did her chemistry homework for her,” Kutcher, 39, recalled of his costar-turned-wife 20 years ago. “I think I was her first kiss, like, on the show. We have our first kiss memorialized on a TV show!”

While the fact that they shared their first kiss on TV and are now married is adorable, Kutcher said it was awkward at the time.

“It was really weird. I was like, ‘Isn’t this illegal?’ I don’t know, and it was really awkward, because I’m like a 19-year-old kid,” he explained to Stern. “She was 14! She was like my little sister. I wanted to make sure she was OK.”

Kutcher went on to dish that Kunis had a teenage crush on him.

“She has … a diary from when she was a kid where she wrote, ‘Oh, this guy’s hot,'” Kutcher dished. “She thought I was cute! At first I think she thought that I was good-looking, and then 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.”

Fast-forward to July 2015, when Kutcher and Kunis tied the knot after dating for 3 years. The couple are also now the parents of daughter Wyatt, 2, and son Dimitri, 6 months.