On the August 7 airing of MBC's 'Oppa Thoughts', actress Park Si Yeon, Sungjae, and Eunkwang joined as the guest. 

During the show, the MCs startled Sungjae by revealing they have a special message from his ''ex-girlfriend." A mysterious girl and the back of her head then appeared on the screen and said, "I'm close oppa-dongsaeng with Sungjae. When I first started going on variety shows and didn't know what to do, oppa told me, 'You're a person with your own unique vibe. Don't try hard to impress everyone.' He's only one year older than me but he acted like such an oppa. I thought it was cute."

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At first, Sungjae seemed like he had no clue who the mysterious ''ex-girlfriend' was but soon showed signs of recognition. 

The ''ex-girlfriend'' then revealed to be his former 'We Got Married' wife Joy. She greeted Sungjae with a smile and said, "Our on-screen marriage has ended in the past but I'm always cheering you on in my heart. Let's stay close. Fighting."

After watching the special clip, Sungjae talked about the advice he gave to Joy and commented, "I think I wanted to share a lot since I've experienced variety shows first after 3-4 years of my debut. It ('We Got Married') was during when Joy was busy so she was having a hard time mentally so I often said, 'Joy, you can't be tired like that already. You have to be a pro.''' He showed some signs of regret on his cringy advice and said, "I don't know why I was like that..."