This statement of Scout's takes place in Chapter 14 of To Kill a Mockingbird after Scout discovers Dill under the bed; he has run away from home because his mother pays no attention to him.  After Jem "breaks the code" and reports to Atticus that Dill is there is the house, Atticus tells Dill that he must report his presence to his Aunt Rachel. 

As Dill makes his "way through the leftovers," Aunt Rachel arrives and lets her

Do-oo Je-sus went off in the hall.  He [Dill]shivered like a rabbit. He bore with fortitude her Wait Till I Get You Home, Your Folks Are Out of Their Minds Worryin', was quite calm during That's All the Harris in You Coming Out, smiled at her Reckon You Can Stay One Night, and returned the hug at long last bestowed upon him.

Dill obviously knows that Aunt Rachel is more bark than bite, although he shivers at first--perhaps in anticipation of the same tired phrases to come.  His fortitude consists of bearing up through the litany of phrases that she goes through until she finally breaks weak and allows Dill to stay and hugs him.

Scout said this in reference to Dill. This was a reference to a typical statement Miss Rachel would say. I think it might have occured after the kids claimed they were playing strip poker but were really sneaking into the Radley's backyard... it is the only time I can think of that Scout, Dill and the adults would have all been talking together.

Scout is saying that Dill happily and confidently took Miss Rachel's reprimand and was not necessarily worried about the consequence she might have had for him at home. He was ready to take what Rachel would have had for him in terms of punishment no matter what it was.

In To Kill a Mockingbird, what does Scout mean by "He bore with fortitude her Wait Till I Get You Home . . ."

In Chapter 14, Dill ran away from home (Meridian) because he didn't like his new father and because he felt neglected. He told Jem and Scout an elaborate story of his daring escape. In fact, he just hopped on a train to Maycomb. After Jem and Scout discovered him hiding under the bed, Jem informed Atticus. Atticus allowed Dill to spend the night but he felt it was necessary to inform Dill's aunt next door, Miss Rachel, that he was okay. Miss Rachel scolded Dill for doing something so irresponsible. Dill "bore" her reprimands and in the end, Miss Rachel sympathetically gave him a hug: 

He bore with fortitude her Wait Till I Get You Home, Your Folks Are Out of Their Minds Worryin‘, was quite calm during That’s All the Harris in You Coming Out, smiled at her Reckon You Can Stay One Night, and returned the hug at long last bestowed upon him. 

Later that night, as Scout and Dill discuss things such as where babies come from, Scout tells Dill that he shouldn't run away just because he feels out of place or neglected. Then Scout asks Dill why Boo, who clearly must feel out of place, has never run away. Dill responds, "Maybe he doesn’t have anywhere to run off to…" Harper Lee uses this incident with Dill to suggest an even larger idea about Boo, that he stays in his house voluntarily because he has nowhere else to go where he might fit in.