how do i threaten my boss to give me a raise

Ok so. You have to be careful with this one, because too much aggression will send you to prison, but too little will ruin your reputation.

+ ﾟ * ｡ For legal reasons, this is a joke ｡⁠ * ﾟ⁠ +

My advice would be, attack something personal, like their family, and say something among the lines of "oh poor little ol' me, who has no money and so many taxes to pay" in an overly dramatic way, extra points if you throw yourself in a sofa or something.

After that, show them a picture of their family "btw look at what I found! I heard X school (where the children go) is really expensive... And this other adult is so pretty that could look good on my wall! Haha just kidding!" What does that mean exactly? Let the boss decide on their mind. And then add "I don't know who they are tho, but I thought that they could be my lucky charm, so I was debating on picking them up" and hold eye contact with a confident smile until the boss looks away. Even if they say something or get aggressive, keep holding the contact and evade with "oh it's just a joke, but the adult had car keys for Y car, thought it was interesting" just drop information you have, right?

After the boss finally looks away, you put your hand on their shoulder to assert dominance and say playfully "anyways! About that raise!"

If it doesn't work, you can always kidnap one of the people and send your boss a fake finger or something. But while the person is in your care, treat them nicely, they will be really scared and this isn't their fault, we want to scare the boss, not the family.