In North America, a sideshow is an extra, secondary production associated with a circus, carnival, fair, or other such attraction. They historically featured human oddity exhibits, preserved specimens
Painting on sideshow truck, firebreather, Florida, 1966
Elly del Sarto, a sideshow performer, in c. 1910
Decaying sideshow advertisement, Florida, 1966
A human blockhead is a carnival or sideshow performer who hammers a nail or other implement into their nasal cavity via the nostril.
Sideshow
…such as the Fiji Mermaid), live animal acts, burlesque or strip shows, actually or ostensibly dangerous stunts, or stunts that appear painful like human blockhead. Most modern sideshows feature fewer to no animal acts, and have a greater focus on trainable feats or consensual body modification rather than exhibiting…
Performing human blockhead
Professional sideshow performer, Captain Darron von Awesome of Tinderbox Circus Sideshow, who can perform this variation of the human blockhead
Close-up of the human blockhead using a 6-inch (15 cm) nail
Sideshow performer, Herbie Hatman of 999 Eyes Freakshow, blockheads a butter knife