reverse rows

function onOpen ()
{
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var menu = [{name: "Reverse", functionName: "reverseOrder"}];
  ss.addMenu("Extra", menu);
}
function reverseOrder()
{
  var range = SpreadsheetApp.getActiveRange();
  var values = range.getValues();
  range.setValues(values.reverse());
}