img = document.createElement("img");
_img.style.position = 'absolute';
_img.style.margin = '0';
_img.style.zIndex = '1000';
_img.onload = function() {
document.body.insertBefore(_img, document.body.firstChild);
setInterval(function(){
document.getElementById('char1').style.left = Math.floor(Math.random() * (window.innerWidth - _img.width))+'px';
document.getElementById('char1').style.top = Math.floor(Math.random() * (window.innerHeight - _img.height))+'px';
var randomRot = (-45+Math.floor((Math.random()*90)));
document.getElementById('char1').style.transform = 'rotate('+randomRot+'deg)';
document.getElementById('char1').style.webkitTransform = 'rotate('+randomRot+'deg)';
}, 1500);
}
_img.id = "char1";
/* you can use whatever image you like */
_img.src = "https://i.imgur.com/FmXCDNG.gif";