I like to think of Shaco as Agendered

I mean if you think about it, They always wear baggy pants, but when they aren't, you don't see anything, do you? Obviously they have a flat chest so they can't be female. Their voice sounds masculine with a tint of femininity, but not a lot. Shaco is always wearing a mask, so you never know what their face looks like and when they aren't wearing their traditional Jester's hat, you can see that they always have very long hair. The only mustaches Shaco dons are for thematic purposes and are attached to a mask. Shaco has a very curvy form, as well. Quite hourglass in figure.

Pictured: The world's tightest corset. https://gyazo.com/11b1dd305eba1056ac91b1f6aadbf62c.jpg

The way in which Shaco kills has a lot of grace and finesse to it, somewhat akin to how a female would kill, if they had to. Shaco is very thin and lithe, not muscular in any way.

There you have it, undeniable proof that Shaco is, in fact, an Agendered Demon Jester.