a humorous perversion of substantial, intended to suggest ‘drunken’: cf. cup (n. pl. the drinking of intoxicating liquor)
From: Phillip Stubbes's Anatomy of the Abuses in England in Shakspere's Youth, A.D. 1583
Part I, Edited by Frederick J. Furnivall, 1877-9
Folly of the Zodiacal Signs influencing men.