A freak show is an exhibition of rarities, "freaks of nature"-- such as unusually tall or short humans, and people with both male and female secondary sexual characteristics--and performances that are expected to be shocking to the viewers. Heavily tattooed people have sometimes been seen in freak shows, as have fire-eating and sword-swallowing acts.
The term "Freak show" is archaic and widely seen as pejorative,
shows such as mentioned and at Coney Island above are more politely termed sideshows.
See also