Email safe word

[Sonia]

In an email [thread], a word (usually irrelevant and strange in the context of the email thread) agreed to by the participating parties to change the subject or end [the thread] when the inappropriateness of the thread has reached its limit. This is so that someone on the email thread can let everyone else know that they feel like continuing the thread would only get too personal and cause shame.
Similar to a [safe word] in BDSM.