A lengthy contraction. Use it your own way, who knows what it actually means. It’s too rusty to translate. The word can be found on Reddit, Tumblr, and probably more, most likely originating on social media.
Mike: who'd'ven't'f'I'dn't've'nt'f'I'd'ven't'f'Ihavn'tn't'd'I've-
John: Mike, shut up, we’re in an interview
John: Mike, shut up, we’re in an interview
by SomebodyNamedFjord April 3, 2020
Get the who'd'ven't'f'i'dn't've'nt'f'i'd'ven't'f'ihavn'tn't'd'i've mug.