Green’s Dictionary of Slang

-bag sfx

[SE bag/bag n.1 (1f); the implication is of being a receptacle for something, most usu. sperm; note also bag n.1 (3)/bag n.1 (5)]

[1910s+] a sfx used in comb. with another term, usu. a n., to describe a contemptible, despised person; when of a woman, often with implications of promiscuity; see cits. at dirtbag n.; fuckbag under fuck n.; gab-bag under gab v.; hornbag under horn n.2 ; jitbag under jit n.3 ; piss-bag under piss n.; scruff-bag under scruff n.; sleazebag under sleaze n.