Zincoshine was a compound made up by Homer Hickam and his friends when they were designing homemade rockets, and it acted as rocket fuel. Attempting to launch their rockets higher and higher into the sky, they determined that the rocket candy fuel they had been using wouldn't get them any further. Quentin, the primary chemist in the group, thought a combination of zinc and sulfur would be more combustible and, if used properly, could propel the rockets further.
Quentin was correct in his assumption that it would be more combustible, but because the materials were not bound properly (the zinc and sulfur were unable to chemically merge without a strong binding agent—a chemical that would facilitate a chemical merging reaction), they violently spontaneously combusted during launch and destroyed the rocket. The group realized a pure grain alcohol (100% alcohol) would be able to be used as a proper binding agent, so they stole moonshine for this purpose. When combined, the mixture worked as intended, and it was dubbed "Zincoshine" for the zinc and moonshine components.