According to a poem by Shel Silverstein what do Sarh Cynthia Sylvia stout not do?

You're thinking of the poem "Sarah Cynthia Sylvia Stout Would Not Take the Garbage Out" by Shel Silverstein.

Sarah Cynthia Sylvia Stout does not take the garbage out. This is the main point of the poem, which humorously describes her stubborn refusal to do this chore.