RGB

Red is not a colour they say.

Just a hue, made by you,
in your head, until your dead.

And neither's Green for that matter.
Another hue that's up to you,
despite the pile of greenish bile
in your hanky when you blow,

you know for sure, that ain't snow.

There's no clue to hue in Blue,
It's yellow and green, what a con
mix together and both are gone
just leaving blue inside of you.