HAHAHA.... they referenced BOTH of the things that happened last year around New Year's in the story. Both the part-time work at the shrine and the 'whiskey bonbon' event at Raku's place. This is about to get silly as they get drunk on amazake (I know what it's called thanks to having watched Kimi ni Todoke, where the New Year's visits that coincided with Sawako's birthday involved the characters enjoying the beverage, and they left it untranslated).
And it's kinda bittersweet seeing Kosaki and Chitoge talk when they don't realize they're referring to the same guy. Gonna be more painful watching them try to encourage the other once one finds out. It feels like there's going to be a moment like that, where one tells the other to go to him, knowing that means giving up their bid.