1. [mid-17C+] nonsense, a trifle, nothing at all; flattery, humbug; also as bag of moonshine, moonshine in the mustard pot.
2. [late 18C+] (also m.s.) illicitly distilled or contraband liquor [fig. use of sense 1 above].
3. [20C+] adulterated liquor.
[late 18C–late 19C] nonsense.
SE in slang uses
[1950s] (W.I.) a party to which anyone can come as long as they contribute food or drink. It is held outdoors under the light of the moon.