I don’t/couldn’t give a monkey’s
Definition 1 of 1
Pro Tip 1/3Colloquial British
A very informal British expression used among friends or in casual conversation, not for formal situations. 
They're arguing over politics again, but I couldn't give a monkey's.
Pro Tip 2/3Humorous Tone
Often carries a playful or ironic tone, rather than expressing strong apathy. 
You're trying to impress with fancy cooking? I don't give a monkey's, just order pizza!
Pro Tip 3/3Emotional Distance
Indicates emotional detachment or disinterest in the subject mentioned. 
He's bragging about his new car, but honestly, I don't give a monkey's.