Ivor Baddiel, the writer and director of a film about anti-Semitism, has asked football supporters to carefully consider their use of the Y-word.
The 55-year-old is the elder brother of comedian David Baddiel and has been attending matches at Stamford Bridge for 42 years. He is determined to educate fans of all clubs about anti-Semitism.
Baddiel's film was launched earlier this year, with anti-discrimination charity Kick It Out, as part of Chelsea's 'Say No to Anti-Semitism' campaign.
The short film intersperses footage of anti-Semitic chants, gestures and social media posts by football fans, alongside images from the Holocaust.
Tottenham supporters use the Y-word in large numbers, often about themselves, and there have been alleged uses of the word by fans from rival clubs, including Chelsea and Arsenal, in the last two weeks.
"Part of the education of it is, absurd as it may sound, even when fans are chanting the most horrible stuff, they might think they're just being anti-Tottenham," Baddiel told Press Association Sport.
"But when you're chanting 'Spurs are on their way to Auschwitz'... that's the level you have to go to to show this is not just anti-Tottenham, this is horrendously anti-Semitic."
Recent incidents allegedly involving Chelsea supporters, which prompted a UEFA investigation, and Arsenal fans have heightened awareness of the issue, which could come back into focus as Chelsea and Tottenham have been drawn together for next month's two-legged Carabao Cup semi-finals.
Chelsea chairman Bruce Buck said this week that Chelsea, including owner Roman Abramovich, who is Jewish, "will not rest until we have eliminated all forms of discrimination from our club", and insisted the use of the Y-word by Spurs fans was not a defence.
Former Prime Minister David Cameron in 2013 backed Tottenham fans' right to sing the Y-word.
A few days later Cameron privately admitted he was wrong to David Baddiel, saying he had been caught off-guard. However, his initial comments are the ones that are referred to.
In 2014, the Crown Prosecution Service dropped charges against three Spurs fans for using the word because it could not be counted as "threatening, abusive or insulting".
That adds to the confusion, where there should be none, says Baddiel, whose interest is due to his religion, not his choice of football team to support.
He added: "The vast majority of Tottenham fans are not Jewish. So they're self-identifying using a racist word for Jews, purely because of history and their location.
"It's the equivalent of white people self-identifying as the N-word, purely because of location and history. They wouldn't be doing that in 2018.
"If there's a Jewish Tottenham fan walking down the street and someone comes up to them and calls them a Yid, they have to effectively turn around and say 'are you calling me that because I'm a Jew or a Tottenham fan? I need to know first before I can tell you whether I'm offended'. It's a ridiculous confusion."
The Baddiel brothers in 2010 worked with Kick It Out to produce a film, featuring Ledley King, Gary Lineker – both former Tottenham players – ex-Chelsea ace Frank Lampard and Kieran Gibbs, then of Arsenal.
'The Y-Word' was intended to heighten awareness that the language is a racist slur. He believes, anecdotally, the situation has improved in the eight years since.
Baddiel expects the recent scrutiny on discriminatory language will make people consider their language carefully in next month's double-header between Chelsea and Spurs.
He added: "Real change takes a long, long time. There will always be animosity between rival fans. It's just finding another way to express it."