Lee Joon and Oh Yeon Seo found a restaurant on MBC "We Got Married 4" to learn cooking. The foreign cook who was teaching them how to cook suggested them to call each other with a nick name, and Lee Joon suggested Oh Yeon Seo to call him 'oppa.(older brother)' When she called him 'oppa,' Lee Joon made people laugh by saying "Lets just keep it the way it was." 

Oh Yeon Seo said "Mom told me to practice to be cute," and Lee Joon replied saying "I feel really awkward." The fans responded saying "Lee Joon warned her," "She was cute," and "Lee Joon got shy."