Get random gif from Giphy - might be against their TOS, please check yourself and use reasonably - I use it for our continuos integration status monitor, which of course is almost never red ;)

gif.php

// get random image from Giphy
function getRandomGif($topic = 'fail') {
    $data = file_get_contents("http://giphy.com/search/$topic");
    preg_match_all('@href="/gifs/(.*?)"@', $data, &$matches);
    $gifId = $matches[1][array_rand($matches[1])];
    return "http://media2.giphy.com/media/$gifId/giphy.gif";
}

Giphy have an API too! 👍

function getRandomGif($topic = 'fail') {
  $gif = json_decode(file_get_contents('http://api.giphy.com/v1/gifs/random?api_key=dc6zaTOxFJmzC&tag='.$topic), true);
  return $gif['data']['image_url'];
}

Note: not the best clean and robust way for a HTTP call... Guzzle?