Zángano is Spanish for drone (as in the asexual, genetically identical organisms that form the majority of a bee colony). In some regional dailects, it is used as a term of contempt for a useless, lazy person; in this context the use may be extended to that of a general, mild slur in the sense of schmuck or dumbass.
"Sara es como mi hermana, pero su novio es un zángano."
"Sara's like a sister to me, but her boyfriend's a zángano."
"Zángano!" (contemptiously spoken to someone you find worthless)