When Kodak introduced its first Kodak Brownie cameras making the photography accessible to the general public, skilled professionals weren’t long to wait. And since 1907 postcards were allowed to have a "divided back", it left the front side of the postcard open for image. This opportunity was widely used by people with big imagination. Thus began the golden age of postcards, which lasted until 1915, and more importantly the golden age of Tall-Tale or "freak" postcards.
The process of creating a tall-tale postcard was simple: a photographer took two snaps, the one of a background landscape and another one was a close-up of an object. He then carefully cut out the second snap and superimposed it onto the first. Then he re-shot the brand new combination and it was done.
Here's an exmaple of a creation of a tall-tale postcard.