I should - A British way to say you're being sarcastic. It's like sayin

A British way to say you're being sarcastic. It's like saying you totally disagree but you're too polite to say it straight out.

I should think so. I should say so. I should think not.

I should co-co. I should cocoa. I should think not.

I should say so. I should think not. I should be annoyed.