It’s a chant about gassing Jews. Or they have got one about that at least. Can’t say it’s exactly what you heard.
Sorry. I have to take extreme issue with this. As a 4th generation Millwall fan with a Jewish partner, whom I have a family with, this is an out and out lie. I am not saying that you are deliberately lying, but at the very least you have mistaken something for something else. If I ever heard anything like what you suggest I would happily never return to The Den again. But, I never have.
The only thing I can possibly think of that you may be referring to is when the crowd do a ‘shushing‘ sound. This happens when both the home and away fans are being noticeably quiet and usually coincides with the game being in a bit of a lull. Some Millwall fans will then notice this and make the ‘shuuuusssh’ sound and others will quickly join in. It’s an excellent precursor (imo) to the crowd then letting out a big ‘Miiiiiillllllllllllll’ chant - which somebody mentions earlier in this thread.
Conversely, another reason I think that there has been a definite mistake by you, is because Millwall are the original and only East End football club. Founded in 1885 on the Isle of Dogs and taking their name from the Millwall Dock area.
The club was the leading light of football in London in the Victorian era - pioneers of professional football in the south with the establishment of the Southern League, which the club dominated, as well as admired cup fighters, whose victories over Everton, Preston, Derby and especially the mighty Aston Villa team of the period, on runs to two FA Cup Semi-Finals (1900 & 1903) earned the club the nickname ‘Lions of the South’, which stuck and replaced the original ‘Dockers’ nickname.
What has the got to do with anything you may ask… well, as most people know, the East End was home to a large Jewish community. Many of these followed Millwall, even when the club made the short hop over the River Thames, thousands still streamed through the foot tunnel connecting SE London and the Isle of Dogs to follow their beloved ‘Lions’. It was only later on that the success of Tottenham Hotspur diminished Millwall’s stature as the number one club for London’s Jewish community to follow.
However, as you know, being a follower of a less fashionable club yourself, most of a club’s support (outside the big brand clubs) is passed down through the generations. Therefore, it is true to say that there are many Jewish families following the club to this day & I am certain, just like myself, they would not remain quiet or even dedicated fans of the club, if what you have so causually stated is/was true. That I am 100% certain of.
Certainly, the media would have highlighted it before too, and added it to our many other misdeeds. Indeed, as I have seen them crucify us for a frustrated fan throwing a meat pie near the lineman - ‘Missiles Rain Down’… phone ins on Talksport about throwing the club out the FL etc etc.
Millwall FC does have its problems, I cannot deny that, but I feel people should be careful with what that say & hopefully I have given a reasoned and calm defence of why I think you are incorrect.