The most polite form of this is probably "I don't give a darn." (or "I don't give a hoot" -- but either one is "safe for children").
The rudest form in common use is "I don't give a f*ck"
And the most elaborate variant is undoubtedly "I don't give a flying f*ck at a rolling doughnut"! (Of course, it's used less often because it takes so long to say.)