London - Used affectionately by supporters of Premier League club Tottenham but hurled back by rivals with venom, football chants featuring "Yid" have long been a source of ambiguity in England.
Now football leaders, striving to eradicate anti-Semitism at matches, have taken on the thorny issue.
Whatever the context, using the derogatory term for Jews in chants is not acceptable, and using it risks criminal prosecution, the English Football Association has ruled.
"The FA would encourage fans to avoid using it in any situation," the organization announced.
Fans of Tottenham, which has traditionally drawn a large fan base from the Jewish communities in London, have been calling themselves the "Yid Army" for decades.
And Tottenham officials have always been careful not to condemn their own fan base by stressing that the "call to arms" was intended to deflect anti-Semitic abuse at matches.
But English football's governing body is concerned that "Yiddo" chants that might seem innocuous lead to far more sinister chants.
"The FA is aware that there are sections of fans at certain clubs who describe themselves using the term, or variants of the term, 'Yid,'" the FA announced.
"Those fans claim that use of the term is a 'badge of honor' and is not intended to be offensive.
"Nevertheless, its use is still liable to cause offence to others, whether Jewish or not.
"Also, by using the term in this manner, fans may be clouding the issue by making it harder to differentiate its use by these fans and by those who use the term in an intentionally offensive manner."
While acknowledging that "Yid" is derived from the Yiddish word for a Jewish person, the FA said in England the word has always been "derogatory and offensive" and its use even divides opinion in the religious community.
"In light of the historic and contemporary use of the term, the FA considers that the use of the term 'Yid' is likely to be considered offensive by the reasonable observer," the FA said, outlining how it wants rules on unacceptable behavior that are "simple, understandable and applicable" throughout the game.
Offenders are liable to be prosecuted and handed a lengthy ban from attending matches.
The FA could not be reached for comment on Wednesday on why it issued the new guidelines.
The abuse faced by Tottenham fans returned to the spotlight last season.
During a Premier League match, some West Ham fans were heard chanting about Adolf Hitler and hissing, a gesture widely seen as imitating the sound of the gas chambers used during the Holocaust.
The FA took no action against Tottenham's London rival.
At a Europa League match in Rome, Lazio fans hurled anti-Semitic chants at the visiting Tottenham fan base, leading to the Italian club being sanctioned by UEFA.