My only theory I could come up with is that he's associated as Frisk's friend in Waterfall, and we already know the relationship between the other pair-
Whatever, it still makes absolutely no sense.
“Boba is a tea-based drink that originated in Taiwan in the early 1980s. It most commonly consists of tea accompanied by chewy tapioca balls, but it can be made with other toppings as well, such as grass jelly, aloe vera, or red bean.” :D