Moonshine is the glowing light that comes from the moon, and it's also a common term meaning "homemade liquor." In an old-timey bluegrass song, a character might drink moonshine in the moonshine.
While moonshine can simply be a synonym for moonlight, it's often used as slang for bootleg (or illicit) whiskey, as well as a colorful way to say "nonsense." For example, you could say, "I listened to her speech, but I finally decided everything she said was nothing but moonshine." This "without substance" meaning is actually the oldest figurative definition of moonshine, dating from the fifteenth century.