We have a World Record

We being Australia, that is.

Australia Wins: Most Devastating Animal Introduction
In 1859, a farmer introduced 24 wild rabbits to Australia. With few natural predators, they bred to calamitous proportions. They eat crops, destroy seedlings, and their burrows damage the soil. Today, there are up to 300 million rabbits in Australia.

thanks Guiness Book of World Records

Anyway, you can hardly blame them for breeding when their wives look like this. Thank goodness they aren't all Crazy Rabbits