What superstition do the children have in connection with the Radley house?

They have all sorts of "tall tales" and superstition that have grown in their imaginations.

"Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that's why his hands were bloodstained -- if you ate an animal raw, you could never wash the blood off. There was a long jagged scar that ran across his face; what teeth he had were yelow and rotten his eyes popped, and he drooled most of the time."