Define Yiff In Hell Meaning

“Yiff in Hell” is a phrase used by those that oppose the furry fandom, directly aimed towards furries as a message to take the activities commonly associated with yiffing elsewhere

On 4chan, “Yiff in Hell” is typically found in Furry threads, used as a protest towards furries in an attempt to lower the amount of furry content posted on the site. While it has been seen spammed throughout threads in great numbers, certain self-identified furries have offered rebuttals stating that the argument doesn’t make sense

This is the proper meaning, rather then the "Other ones" trying to insult the Furry Fandom

what people say to furries.
most commonly used by anti-furry groups.
Is seen as a deep insult to people who use it.