A "Flarvarian Float" is a type of drink served in the galaxy. Sylvia ordered one of these for herself and Wander while the latter was talking with Trudi Traveler. The drink remains in the planet when Sylvia and Wander decide to go through the planets Trudi visited.
Later, after realizing he had been doing everything wrong, Wander returned to join Sylvia in drinking the beverage. When the two grabbed it, however, they fought for the chance to drink it.
The drink has a light-ish green color, and It's usually served in a glass cup.