Whats the easiest way to shut up my pet cat?

Okay, PRESUMING that you aren't a troll (though I am pretty sure you are)… a few questions... is this a female? How old is she? Is she spayed? 

If the answers are 1. "Yes, she is female", 2. "She is 6 months or older", and 3. "No, she's not spayed"-- the answer here is... wait for it... "Get her spayed".

If the answer to 1. is "No, he a male", and the answer to 3 is "No, he's not neutered... he is still intact (has his 'balls')" the answer is... "Get him neutered"

If the answer to 3 is "The cat is fixed", try playing with the cat. 

If the cat is elderly and the vocalizing is a new behavior, get to the vet for blood work including thyroid testing and if the cat has an overactive thyroid-- get the cat on medicine.

If the cat is hungry... feed the cat.

Get a dog. That'll shut it up.

Euthanasia would shut him up

Refuse to discuss politics & religion with your kitty.

Give him treats

Feeding her tin of tuna usually works with my kitty. A bellyful of tuna and off to sleep she goes.

Buy a squirt gun and spray until it stops. It will learn sooner or later.

See what your cat wants and do it.