Object - In

A T extension method to determines whether the object is equal to any of the provided values.

Try it

public static void Main()
{
	int searchVal = -1277;

    // C# Extension Method: Object - In
	Display(searchVal, searchVal.In(32767, 235, 0, -1277, -32767));
	Display(searchVal, searchVal.In(32767, 235, 0, -1278, -32767));
    
}

public static void Display(object searchVal, bool status)
{
	if(status)
	{
		Console.WriteLine("{0} is in the list.", searchVal);
	}
	else
	{
		Console.WriteLine("{0} is not in the list.", searchVal);
	}
}

View Source 
using System;

public static partial class Extensions
{
    /// <summary>
    ///     A T extension method to determines whether the object is equal to any of the provided values.
    /// </summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <param name="this">The object to be compared.</param>
    /// <param name="values">The value list to compare with the object.</param>
    /// <returns>true if the values list contains the object, else false.</returns>
    public static bool In<T>(this T @this, params T[] values)
    {
        return Array.IndexOf(values, @this) != -1;
    }
}