Meaning of querusa by Anónimo

I have heard and understood (with my 70 years) when I was a kid, which means "to do or look at something disguisedly" example: the spark (he looked) of querusa (with dissimulation); He passed him the cigarettes of querusa. In prison language "the querusa" is that talking becomes handsome and is not. Regarding the saying "Isolina the croaker, from querusa the hake" there can be different explanations: 1) that points to Isolina the corvina and it afane of Querusa the hake . 2) in the Buenos Aires slang "Isa or iza" meant to pay attention or be careful / caution, example: hoist the gray hair, Isa the button, etc. but so that it is not so obvious this "alert" was replaced with the name Isolina and thus said 'ISOlina with morphi'. Then the saying can be translated as : Isolina ( be careful with . . . ) the corvina and querusa ( secretly ) takes the hake.