Mila Kunis, Ashton Kutcher Caught Kissing In A Tree In New York City’s Central Park

Mila Kunis and Ashton Kutcher's relationship is going strong.

The couple exemplified the taunting K-I-S-S-I-N-G nursery rhyme in the streets of New York City's Central Park on Monday. They were nestled against a large tree as they shared a lengthy passionate smooch.

They looked casual, Kunis, sporting loose sweats and Kutcher, in jeans, a white T-shirt and baseball cap.

"They held hands and were very affectionate," a bystander told People Magazine. "They seemed to enjoy exploring the city together. They looked very relaxed and seemed very happy together."

Kunis - who met Kutcher while filming the wildly popular TV show "That 70's Show" admitted she shared her first kiss with the actor on set in 1998 -- when she was still a teenager.

"I was like, 'Oh, he's so cute, it's the Calvin Klein model!' " she explained. "Then I was like, 'I have to kiss him?' I was so nervous and uncomfortable. I had the biggest crush on him."

Years later, Kutcher was shocked to learn the news. "I'm the first guy she kissed? Oh my god, I had no idea!" he exclaimed. "I'm so glad I didn't know that or it would've been too much pressure."

Adding, "I was so nervous. She acted so cool. She seemed as if she'd done it a thousand times. I was the one with the butterflies in my stomach. I mean, here's this little girl and I have to kiss her. It was nerve-racking."

The couple went public with their relationship in April and have since taken a romantic getaway to Bali. They nested at a five-star resort on the island's southern peninsula which boasted amenities like "a sunken indoor bathtub, a private pool and a wooden four-poster bed."

"They were smiling, really relaxed together," an onlooker said of the adorable travelling duo.