Interact with a choppa is in the Marshfang Spider cave in the Marshes of Madness area. This unlock contributed to the Marsh Choppa achievement category. Location is (32571,5243) in the Marshes of Madness zone.
The life of a greenskin can be broken down into two distinct categories: scrappin' and not-scrappin'. While pursuing the former (and preferred) category, most greenskins choose to arm themselves with some type of weapon. Often, said weapon is nothing more than a ripped-out fence post or metal bar, but sometimes a greenskin is lucky enough to come upon something with an edge.
These wedges of edged steel are known as choppas, and the size of one's choppa is directly proportionate to the size of one's pile. This 'marsh choppa' is one of exceedingly large size, and promises to be more than capable of shaving of a few stunty bears (and heads).