More on Get One's Back Up from Infoplease:

• Get One's Back Up - Get One's Back Up (To). To show irritation, as cats set up their backs when angry. Source: ...
• back: meaning and definitions - back: Definition and Pronunciation
• Back and Edge - Back and Edge Entirely, heartily, tooth and nail, with might and main. The reference is to a wedge ...
• Dictionary of Phrase and Fable: G - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "G"