Once saw a clown say clowns & furries speak the same "silent language" and that stuck with me for some reason
i bet this has to do with something called Mask Work in theater, which focuses on how masks can make a person automatically emote physically in a whole different way.
The one fact about Mask Work that will tell you everything you need to know about why i say this is: people, for whatever reason, tend to behave the same ways in the same kinds of masks.
So for example, people putting on variations on this classic
all have a tendency to push their heads forward, raising their shoulders and curving their back, and to move their heads with a bit of a twisty movement, constantly looking to one side or the other with twitchy head movements when not laser focused on something. This happens the first time a person spends open-minded time in the mask, usually in front of a mirror, and it happens whether or not the person has ever seen someone else wearing the mask.
Many mask designs produce an effect that people sometimes describe as being possessed by the mask, as if the mask has a character all of it’s own that shines through no matter who is wearing it. Some masks make people have a tendency to flounce, other masks will encourage slithery movements.
And people tend to agree that the masks do not talk (that is, people trying to embody the masks do not feel like they can say words and be in the character of the mask) but that they do vocalize - so one mask may seem to make people make a sort of grumbly gibberish, and another will tend to encourage people to make sort of nasally “fnee ... fnee” noises.
Anyway, the clowns and furries silent language thing has to do with this i think.
Of course the sentence also serves as a quiet knowing look about the way both groups get similarly unwarranted, visceral reactions from much of the public -- a nice play on words from the clown there, who, after all, is an entertainer.
perhaps-perhaps-not