The Collaborative International Dictionary of English v.0.48:

Slubber \Slub"ber\, v. t. [imp. & p. p. Slubbered; p. pr. &
   vb. n. Slubbering.] [Cf. Dan. slubbreto swallow, to sup up,
   D. slobberen to lap, to slabber. Cf. Slabber.]
   1. To do lazily, imperfectly, or coarsely.
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            Slubber not business for my sake.     --Shak.
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   2. To daub; to stain; to cover carelessly.
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            There is no art that hath more . . . slubbered with
            aphorisming pedantry than the art of policy.
                                                  --Milton.
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