HYDRO and FLUID

Floating Egg (1x12)

:

n an amusement park, Hydro and Fluid run to the roller coaster. At the entrance, a sign with the minimum height to enter the ride stops Hydro from getting in. A forbidden sign is enough for Hydro to use his knowledge to make his own water salty, allowing a dinosaur egg to float inside his head, making him tall enough to go for a ride on the roller coaster. But how is Hydro going to keep his water in, since the top of his head is open?