The etymological root of so-and-so could be found in the Egyptian language, although its origins are unclear. It can be said that fulano derives from the Hispanic Arabic fulán , in turn from the classical Arabic fulān .
This term is used to refer to a person whose name is unknown . For example: “Who is that guy who is talking to Marta?” , “Yesterday a guy came to the business to ask how he could get to the Church of San Juan” , “A guy scratched my car door with the handlebar of his bicycle and, instead of stopping and apologizing, he fled at full speed ” .
Depending on the country, there are many other ways to refer to the subject with an unknown name. As a synonym for so-and-so, names such as mengano , sutano , perengano , monteto and magoya can be used, or even their diminutives: fulanito , menganito , etc. Another possibility is to resort to names like Juan Pérez , Juan González , Juan de los Palotes or Perico de los Palotes .
The idea of so-and-so can also be used when you know the name of the individual, but you do not want to express it : “Today I met so-and-so again and he continues with the same position,” “If so-and-so comes, give him the envelope that is on my desk.”
Another possibility is that so-and-so refers to someone imaginary or undetermined : “If so-and-so comes into the store and buys any product from me, I will give him the merchandise and the corresponding invoice,” “I am proud of what I did and I am not going to tolerate Let so-and-so or so-and-so question me about it.”
So-and-so can have a derogatory connotation : “The so-and-so who hosts the evening news always says stupid things,” “She's not my girlfriend, she's a so-and-so who I meet when I don't have a better plan.”
In the same way, we must not overlook the fact that when used in the feminine it can also be used as a synonym for prostitute. Thus, an example would be: "Manuel did not hesitate to admit that he went to a whore's house to enjoy sexual relations."
In addition to everything indicated, it is also necessary to take into consideration that the word in question, even its feminine version, has been used on numerous occasions to give titles to cultural works of different kinds. This would be the case, for example, of the novel “Yo soy so-and-so.”
It is a book written by Álvaro de Laiglesia, which was published in Spain in the 1960s and whose protagonist is Mapi, a humble village girl who since her early childhood has suffered a life full of setbacks and problems. Thus, she will lose her father when a plane hits him while he was repairing a roof, serious financial problems will arise in her family, her mother is not an easy woman... All of these situations that, due to different vicissitudes, will end up turning her into a prostitute.
In the same way, in cinema we also find films that use the term in question in their title. A good example of this is the film “Fulano y mengano”, which was released in 1955 with Joaquín Romero Marchent as director.
Actors of the stature of Pepe Isbert, Julia Martínez, Juanjo Menéndez and Emilio Santiago make up the cast of this feature film that is based on a novel by José Suárez Carreño.