In these games, they are called Ultra Syrups. When one consumes it, it restores 100 Bros. Points. They are sold at the Castle Town Item Shop for 80 coins after Princess Peach is kidnapped. Birdo has a chance of dropping the item with 100%, Magikoopas has 22.58% chance, ????'s Sharkbone variants have 16.13% chance and Sniper Bill with 12.9% chance.
The other game, it restore 60 Bros. Points instead of 100.