horsefeathers!
horsefeathers! {n. phr.}, {slang}
1. Not true; I don't believe what you're saying.
"Horsefeathers!" Brad cried. "I can't believe a word of what you said about Jessica."
2. Exclamation of disgust.
"Horsefeathers!" Fred cried. "We've just missed the bus."
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Source: A Dictionary of American Idioms