The pair, who wed in 2015, looked momentarily surprised before Kutcher lent over to give his wife a big kiss.
Naturally, the comedy actor had to give fans a laugh, trying to go back for a french kiss afterwards.
Kunis pushed her husband away and burst out laughing.
The pair, who generally keep their love life under wraps, are no strangers to kissing on camera. They shared their first-ever kiss on That '70s show.
"I think I was her first kiss. On the show -- we have our first kiss memorialized on the TV show. . . . It was really weird. I was like, 'Isn't this illegal? Like, am I allowed?' It was really awkward, cause 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," Kutcher previously revealed on The Howard Stern Show.