In Tom's testimony in Chapter 19, he tells Atticus that he often has to go by the Ewell home on his way to work each day. He explains that he works steadily for Mr. Link Deas all year round.
Accordingly, Tom asserts that Mayella asked him to 'bust up a chiffarobe' for her the previous spring. A chiffarobe is a piece of furniture with drawers and a space for hanging garments. Here are some images of chiffarobes.
Tom says that he remembers it was last spring because it coincided with the new planting season. He remembers that he had his hoe with him at the time. When he admits to Mayella that the only tool he has to chop up the chiffarobe with is the hoe, Mayella lends him a hatchet. After he finishes, Mayella comments that she should probably pay him a nickel for his labor. However, Tom refuses to accept payment for his work.
He tells the court that he goes inside the fence regularly because Mayella always seems to have chores for him to do. He describes chopping up kindling and carrying water for her.
When Atticus asks Tom to tell the court what happened on the evening of November 21st of the previous year, Tom tells the court that he thought Mayella had more wood for him to chop up. Instead, Mayella wanted him to fix an old door which was supposedly coming off its hinges. However, when he checked the door, it appeared to be fine. Mayella then tells Tom that it took her a year to save up enough money so the children could go for ice-cream in town.
Tom tells her that it was very nice of her to do that. Mayella then asks Tom to grab a box for her from off the top of a chiffarobe. However, when he does so, she grabs him by the legs. Tom is so shocked that he knocks the chair over after hopping off of it. He tells the court that Mayella subsequently pushes herself on him, kisses him, and propositions him. When he sees Mr. Ewell at the window, Tom runs for his life.