Green’s Dictionary of Slang

(US) any viscous, treacly substance, often a foodstuff.

1911		L. Pound ‘A Second Word-List From Nebraska’ in DN III:vii 544: goozlum, googlum, n. Used of syrup, molasses, etc., at table. ‘Pass the goozlum for these flapjacks.’.
1925		J. Stevens ‘Logger Talk’ AS I:3 137/2: Gravy is ‘goozlum’ or ‘sop’.
1931		Irwin Amer. Tramp and Und. Sl. 88: Goozlum. — Gravy.
1949		Monteleone Criminal Sl. (rev. edn) 105: goozlum Gravy.