It is also quite bizarre to suggest that the word "cracker" is as detestable an ethnic slur as "nigger", as Kent Davis and musicmic have. As the M-W definition notes, there is also a perfectly innocuous use of the word which is relevant to a specific cultural group from the American south: Georgia and Florida, to-wit:

The Tropic of Cracker (published by University of Florida Press)

"Ecology of a Cracker Childhood" (by Milkweed Editions Press)