The terms "bullshit" and "horseshit" refer to the truth or untruth of information. "Batshit" and "Apeshit" refer to ones mental state. "Chickenshit" refers to someones lack of courage or fear.

Why do they mean such different things, and why do we use those particular animals as "shit" adjectives? Why don't we call things "frogshit" or "dolphinshit" or "goatshit"?