One of the ways The Great Depression upsets the traditions and expectations of the Joad family — and many other families — is through gender roles. Pa says this line as a bit of a joke about getting a stick to beat Ma, as punishment for her stepping out of her traditionally subservient role as wife. Because she has made the decision that the family will leave the government camp, and because she was so confident and direct in her delivery of this pronouncement, Pa feels she is usurping his role as the head of the household and decision-maker. 

He is teasing her a bit, as he also says, "Now, Ma, don' think I don' wanta go. I ain't had a good gutful to eat in two weeks." Still, Ma drives the point home, saying: 

"You get your stick, Pa, [...] Times when they's food an' a place to set, then maybe you can use your stick an' keep your skin whole. But you ain't a-doin' your job, either a-thinkin' or a-workin'. If you was, why, you could use your stick, an' women folks'd sniffle their nose an creep mouse aroun'. But you jus' get you a stick now an you ain't lickin' no woman; you're a-fightin' cause I got a stick all laid out too."

Pa doesn't get angry at this, though. He and Ma both need to be fighters and tough to survive their circumstances.