C# extend method for Enum object

I am trying to create an extension method but can't get it to work.

So this works, create extension method on a Type of enum example:

public enum Pets
{
    ....
}

Above Pets can be extended creating an extension method like:

public static void Myex(this Pets pet)
{
    ... 
} 

But when I try to extend Enum itself example below:

Public static void something(this Enum en)
{
    ... 
} 

And try to use it like below

Enum.something(); 

this doesn't work.

I was trying to create similar method like Enum.Parse, Enum.IsDefined (which are already exposed by c#).