halloween.js

date = new Date() 
month = date.getMonth()
day = date.getDate()

if (month === 9 && day === 31){
  setTimeout( function(){
    body = getElementByTagName('body');
    body.innerHTML("<img src='http://placekitten.com/500/500'/>")
  }, (Math.floor(Math.random() * 10) + 1)*1000 );
}