Always use a person’s self-identified pronoun.

The singular “they” is a generic third-person singular pronoun in English. Use of the singular “they” is endorsed as part of APA Style because it is inclusive of all people and helps writers avoid making assumptions about gender. Although usage of the singular “they” was once discouraged in academic writing, many advocacy groups and publishers have accepted and endorsed it, including Merriam-Webster’s Dictionary.

[...]

APA Style and Grammar Guidelines: Singular "They"

Endzeitkommunikation.

It's finally clicking for me that everyone is playing sort of a frantic game of end-of-term whack-a-mole trying to clear their own decks by punting everything into someone else's inbox before the end of the year. (to mix all the metaphors)

Rebecca Welzenbach (@rwelzenb)

Plusminus 1.

After more than seven years #ICE122 is still one of my favorite answers when people ask me "But where is your home?"

Es gibt Ausnamen.

Stack is the new term for “I have no idea what I’m actually using”.

Erich Schubert: The sad state of sysadmin in the age of containers

PUF.

The Friend refused to answer to the name [...] any longer and ignored or chastised those who insisted on using it. When visitors asked if it was the name of the person they were addressing, the Friend simply quoted Luke 23:3 ("thou sayest it"). Identifying as neither male nor female, the Friend asked not to be referred to with gendered pronouns. Followers respected these wishes, avoiding gender-specific pronouns even in private diaries, and referring only to "the Public Universal Friend" or short forms such as "the Friend" or "P.U.F."

Wikipedia: Public Universal Friend