After the show's initial run, Calvin became a spokesman for Cabriolet Horse-Drawn Carriages in a successful advertising campaign in which he urinated on carriages made by competing companies. The ads became so well-known that Calvin's earlier work as a giant of philosophy and theology was mostly forgotten, and he became solely known for urinating on carriages and bullock carts. Over the years, the association has continued and a caricature of Calvin is depicted doing the same on modern motor vehicle decals. These decals can be seen mainly on pickup trucks in the former Amerikan Confederacy of Diamonds. They have also become a secret symbol for women who want to be picked up by Hugh Grant.