object thisLock = new object();

namespace test
{
  class Program
  {
    readonly object _lock = new object();
    void Test()
    {
      lock(_lock)
        Console.WriteLine("lock");
    }
    static void Main()
    {
      new Program().Test();
      Console.WriteLine("done");
      Console.ReadKey(true);
    }
  }
}

.method private hidebysig instance void  Test() cil managed
{
  // Code size       40 (0x28)
  .maxstack  2
  .locals init ([0] bool '<>s__LockTaken0',
           [1] object CS$2$0000)
  IL_0000:  ldc.i4.0
  IL_0001:  stloc.0
  .try
  {
    IL_0002:  ldarg.0
    IL_0003:  ldfld      object test.Program::_lock
    IL_0008:  dup
    IL_0009:  stloc.1
    IL_000a:  ldloca.s   '<>s__LockTaken0'
    IL_000c:  call       void [mscorlib]System.Threading.Monitor::Enter(object,
                                                                        bool&)
    IL_0011:  ldstr      "lock"
    IL_0016:  call       void [mscorlib]System.Console::WriteLine(string)
    IL_001b:  leave.s    IL_0027
  }  // end .try
  finally
  {
    IL_001d:  ldloc.0
    IL_001e:  brfalse.s  IL_0026
    IL_0020:  ldloc.1
    IL_0021:  call       void [mscorlib]System.Threading.Monitor::Exit(object)
    IL_0026:  endfinally
  }  // end handler
  IL_0027:  ret
} // end of method Program::Test