Hot Chocolate is an item that can be acquired in Hometown, at QC's Diner. It does not transfer to the party's Dark World inventory, and does not remain in the Light World inventory in Chapter 2. It can also be obtained in Chapter 4 if the game's state is in a Weird Route upon leaving Noelle's house. Deciding whether to drink it or not, does not seem to affect the Weird Route's progression.
In Chapter 2, the Diner Shopkeeper has slightly different dialogue if she gave Kris the hot chocolate in Chapter 1.