Because the Cantonese pronunciation of "gay" is "gay", gay men are called gay friends. Later, it was widely used and extended to the meaning of good friends. Generally speaking, same-sex men are very close and have better relations than others, and they will also be called good friends.
Some people call each other gay friends when they are engaged in fund trading.
Extended data
This word comes from Hong Kong movies in1980s, and English "Gay" is homophonic with Cantonese "base", so "base" is generally used instead of "Gay" in subtitles. Later, with the spread of homosexual ideas, the word "gay" in Cantonese was used all over China.
Now used in online buzzwords, it usually means irony or ridicule. It also means that there are loving good friends who discuss or are interested in topics together in the ACGN circle.
Gay friends is also often used to address friends on the internet, implying ambiguity and closeness. Broadly speaking, it also refers to buddies, girlfriends, comrades-in-arms, teammates in competitive games, netizens, and particularly good ambiguous friends.