How to hide on page load [duplicate]

I’m making a prank .html page for a friend. The prank was, you would push a button and a phrase would pop up under the button. I figured out a way to hide the phrase and unhide it. The problem is that, when you load into the page, the phrase would already be on the screen. How do I keep it hidden on page load?

function Function() {
  var x = document.getElementById("urmom");
  
  if (x.style.display === "none") {
    x.style.display = "block";
  } else {
    x.style.display = "none";
  }
}
<p>Click the "Try it" button to toggle between hiding and showing the DIV element:</p>

<button onclick="Function()">Try it</button>

<div id="urmom">
  ur mom
</div>

<p><b>Note:</b> The element will not take up any space when the display property set to "none".</p>