title: Override DateTime.ToString to use "o" instead of "G"
body: <p>Is there any way in .Net I can get the default format used by DateTime.ToString() to change from ToString("G") to ToString("o")?</p>
  
  <p>I don't have the option of using a different overload it has to be ToString().</p>
  
  <p>Update:
  I found a way to do what I need using DateTimeOffset but it was very useful to see Gonzalo's solution.</p>