Ding Dong -the sound of a bell ringing meaning “Correct”.
-In Greatest Love Ding Dong was an affectionate nickname given to Gu Hyung Kyu (Ae-Jung’s nephew) by Dokko Jin after their first encounter. Seeing that his aunt had top star DKJ’s number on her phone, he dialed it and proceeded to ask him a bunch of speed quiz questions like his aunt did on Quiz to Change the World (세바퀴); which DKJ couldn’t help but enthusiastically answer all the while demanding to know who was on the other line.
A bit of little cupid, Ding Dong is a big supporter of DKJ, his real-life Ironman (See: Ironman), and his quest to get Ae Jung to like him. He frequently helps the Ae-Jin couple by bringing them together either at DKJ’s home, his own home or even on their outings.
In episode 11, seeing his aunt crying while throwing out the purple sneakers, Ding Dong later goes to the recycling bin to retrieve it back and lovingly washes them knowing how much they mean to her. He also aided DKJ by secretly putting a diamond flower ring that DKJ was intending on giving her in a special place, the purple sneaker shoe box, so that she’d be able to find it later. (See: Ring)
In addition, “Ding Dong” is often used to mean something was answered correctly. Most notably, there are two scenes where this jargon is used. Dokko Jin confesses to Ae Jung amongst the backdrop of an amusement park castle lit up at night and fluttering leaves of cherry blossom trees. He says that someone of his status doesn’t normally rescue damsels from a pathetic reality but he couldn’t just stand by and watch her celebrate her 10 year debut anniversary in a nightclub, eating kimbap. Ae Jung is confused so Dokko Jin continues.
DKJ: There’s only one answer to all this. What do you think it is?
AJ: Dokko Jin-sshi, it can’t be. You like me?
DKJ: Ding Dong.
Ae Jung finally confesses her love to Dokko Jin using antonymic lingo in Episode 14.
AJ: Since I’m not doing what Dokko Jin-sshi wants me to and since I don’t want to sit here counting down the hours, or believing in our success rate and just ignoring it all, I won’t explain it, nickname it or make it complicated. There’s only one answer.
DKJ: You like me a lot.
AJ: Ddeng (땡 – Incorrect), despite what you think, much, much more than you can know… I love you.