most people would believe that you are a teen, because most people would make an assumption that your userid - which you chose intentionally - has to do with your age.

So I visited your profile, see that you are 23, and can tell you that the line in which you say that you are not a HE or a SHE is displayed on some kind of a background which resembles a colorful upholstery fabric, and the font's color is such that the line is completely illegible - I had to select it with the cursor to be able to read it. So the most obvious step towards being called "they" is to make the line legible.

I am curious to learn of the quotes from Shakespeare that use "theirs". Nothing comes to mind from my memory, but I did not read enough of his works. This is a well-known mockery sonnet of his that only uses the female pronouns.

SONNET 130

My mistress' eyes are nothing like the sun;
Coral is far more red than her lips' red;
If snow be white, why then her breasts are dun;
If hairs be wires, black wires grow on her head.
I have seen roses damask'd, red and white,
But no such roses see I in her cheeks;
And in some perfumes is there more delight
Than in the breath that from my mistress reeks.
I love to hear her speak, yet well I know
That music hath a far more pleasing sound;
I grant I never saw a goddess go;
My mistress, when she walks, treads on the ground:
And yet, by heaven, I think my love as rare
As any she belied with false compare.