From the Super Mario Wiki
Mario, Luigi and Paper Mario drinking Lakitea
“Some people like cream and sugar in their Lakitea, but why mess with perfection?”
Lakitu, Mario & Luigi: Paper Jam

Lakitea is a healing item in Mario & Luigi: Paper Jam found exclusively at the Arcade. When consumed, it fully restores the trio's HP and BP. It can be purchased from the Lakitu running the Arcade café for 20 coins, and takes effect immediately upon purchase.