cfj/console.reverselog.js

var _log = console.log
window.console.log = function(log){
  if (Math.floor(42*Math.random()) === 1) {
    _log.call //
  } else {
    _log.call(console, log)
  }
};  // don't mkae it too obvious...

See evil.js.

Also note that string.split('').reverse().join('') is not a very good way to reverse a string in JavaScript.

You are not considering booleans in your code :p I suggest the following improvement:

var _log = console.log;

window.console.log = function(log){
_log.call(console, log.reverse ? log.reverse() : typeof log === 'string' ? log.split('').reverse().join('') : typeof log === 'number' ? log.toString().split('').reverse().join('') : typeof log === 'boolean'? !log : log);
};

And don't forget:

console.log.toString = function(){return _log.toString();};

@mathiasbynens I somehow feel that bulletproof string reversal is not really the main objective here. LOL