What does “Keep your bodily fluids to yourself” mean?

Question

You’re a crazy Feeling Brain– piloted meat robot just like the rest of us. Keep your bodily fluids to yourself, please.

I know the main structure is: keep something to yourself and it means do not tell anyone about something.

But I still don't understand the meaning of the sentence.

So, could you please explain it to me?

The fuller text is:

This is the Classic Assumption, the belief that our reason is ultimately in control of our life and that we must train our emotions to sit the fuck down and shut up while the adult is driving. We then applaud this kidnapping and abuse of our emotions by congratulating ourselves on our self-control. But our Consciousness Car doesn’t work that way. When his tumor was removed, Elliot’s Feeling Brain got thrown out of his moving mental vehicle, and nothing got better for him. In fact, his Consciousness Car stalled out. Lobotomy patients had their Feeling Brains tied up and thrown in the car’s trunk, and that merely caused them to become sedated and lazy, unable to get out of bed or even dress themselves much of the time. Meanwhile, Tom Waits was pretty much all Feeling Brain all the time, and he got paid copious amounts of money to be drunk on television talk shows. So, there’s that. Here’s the truth: the Feeling Brain is driving our Consciousness Car. And I don’t care how scientific you think you are or how many letters you have after your name, you’re one of us, bucko. You’re a crazy Feeling Brain– piloted meat robot just like the rest of us. Keep your bodily fluids to yourself, please.

Answer 1

The book you've quoted, Everything is F*ked: a Book About Hope, is using a metaphor that the human mind is the "Consciousness Car", and that there are two drivers, a Feeling Brain and a Thinking Brain. (The quote is on page 28.)

I won't go too deeply into how the metaphor unpacks because that's what the book does, but this section of the book is attempting to convince you that the reason you do things that are not what you "know" you should do, is because the Thinking Brain is totally subservient to the Feeling Brain. Sometimes the Feeling Brain lets the Thinking Brain drive, but like your dad snoozing in the passenger seat, it's entirely up to the Feeling Brain when that starts and ends. Feeling Brain wants to drive now, get the hell in the back seat, Thinking Brain.

"You're a crazy Feeling Brain-piloted meat robot just like the rest of us." This means, don't kid yourself; you're just as subject to your feelings as everyone else. "Keep your bodily fluids to yourself, please" is a follow-on to this "meat robot" image. Mostly it's just a color statement capping the "meat robot" image. There's also an undertone that it is advising you to try not to drool on people or cry publicly -- see, these are bodily fluids -- or, by analogy, let other emotional behaviors get you in trouble.

Answer 2

It means "don't get your bodily fluids on other people". I have no idea how it relates to the rest of the paragraph. My guess is that it's a reference to an earlier anecdote involving bodily fluids.