I'll know soon enough because it is bound to happen for me. I've broken off a bunch of fish the last couple years that felt like they were world's records for sure, and a couple I saw in the waves with my eidetic memory were over 100 lbs for sure.
Kidding aside, I'd do what any sane human being would do...try to make a buck off it and laugh all the way to the bank while people bashed me for being lucky....because of course they'd be right. There would never be anything more indicitive of "it is better to be lucky than good" than if I caught the world record.