i'll be a monkey's uncle - This is what you yell when you're so stunned you'd rather be

This is what you yell when you're so stunned you'd rather be stuck with a monkey than your annoying cousin.

'You just passed the class? I'll be a monkey's uncle!'

'You stole my lunch? I'll be a monkey's uncle!'

'You just texted me during class? I'll be a monkey's uncle!'