When talking about Lee Seung Gi's "Because You're My Woman", the guest seemingly remembered it as "Noona Is My Woman".
Sunny then said that she should know the correct title, saying "after all our relationship is like family" (referring to Lee Seung Gi*)
Afterwards when introducing the song, Sunny accidentally said it wrongly (as "Noona Is My Woman"), and the guest laughed at her.
*it is likely that Sunny is hinting at LSG's relationship with Yoona - but it's just a speculation from her words