Had've

A shortened form of "would have (been)". Another — dialectical — variation of this is "had'a".

It's a hypothetical conditional as opposed to 'had been'
—Somewhat prevalent in Australia. And it's also used in Britain, and some parts of the U.S.

Would've; Had'a; Hadn'a; Had've
—Had it have been different, people often wouldn't be such petty assholes