I don't give a shit
You're saying this like you're ready to throw your feces at someone. You're so uninterested that you're ready to physically show them how uninterested you are.
My teacher was going on and on. I said, 'I don't give a shit.'
My sister talked my ear off. I said, 'I don't give a shit.'
My dad asked me about my day. I said, 'I don't give a shit.'