A nasty, paltry fellow. A slub is a roll of wool drawn out and only slightly twisted; hence to slubber, to twist loosely, to do things by halves, to perform a work carelessly. Degullion is compounded of the word “gull,” or the Cornish “gullan,” a simpleton.
Quoth she, `Although thou hast deserved, Base slubber-degullion, to be served As thou didst vow to deal with me.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894