Polari
Polari appeared in a society where being gay was not an option provided that you wanted equal rights and accommodation.

The Polari language was also known as Palarie, Palare, Parlarly and in various other forms and it was exclusively associated with gays and lesbians throughout the 20th century. It was mostly spread in London and it was an important part of the subculture that was being used by people confronted by the legal system that considered homosexuality, and especially sodomy, a criminal offense.

Polari
The legal system considered homosexuality, and especially sodomy, a criminal offense – paulunderhill.com

What makes Polari different than any other language is that it was secret and only was only circulating in small social circles, only being used by those who were interested in the gay culture. The part of the Polari vocabulary that was being used more frequently consisted in using slang words for clothes, different types of people, common everyday objects and it was also used in expressing acceptance of rejection towards sexual inquiries.

Aside from this, Polari also had a vocabulary section that was only used and known by a handful, which included alternative spellings and pronunciations for everyday English common words and notions. If you think this language was a mere caprice, you could not be further from the truth. Polari appeared in a society where being gay was not an option provided that you wanted equal rights and accommodation. It was the language of the stigmatized and it helped them forming a supportive community where everybody was equal to one another and where discrimination was non-existent.

Polari
May we never need another Polari-like language again – tabletmag.com

The fact that Polari died out is not a bad thing, but on the contrary. Because it was an attribute of and anti-social behavior, it was used as a weapon against stigma and this is why today such a language would be pointless. The reason is that the gay community’s fight for equal rights and social acceptance has moved towards the mainstream of the society. We have exchanged the fight for survival with the fight for social acceptance and equality and may we never need another Polari-like language again.