How can I get the 2012 April Fool's joke to appear?

Question

Honest question, I can't seem to get the April Fool's Joke to appear. Is there some condition it requires? Is it only on some sites?

I've heard you just open a tab with an SE site/post in it and leave the tab alone, and when you come back after a while you'll see the joke, but I'm getting no such thing. It's April first in UTC, so the joke should be in effect, and I've heard other users report (and a screenshot) so I don't know why I'm not getting it.

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So we've found your little code, devs, and we're finding the messages. ALL OF THEM.
AHAHAHAHAHAHA

For those playing the Home Game, use your browser's JS console and enter the following code:

 $.ajax({ url: "/clippy/get?id=5", data: { fkey: StackExchange.options.user.fkey }, async: false, type: 'POST' }).responseText

And you'll get an Object back that has Clippy Corn responses. Change the id=5 bit to get different messages. We've compiled a list of known responses below. But you wouldn't be a real Hax0r

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This joke has expired as of 4/2/2012, so read the accepted answer to see all the examples of the joke.

Answer 1

This is indeed very mysterious.

Jeremy Banks pointed out the following little snippet in https://meta.stackoverflow.com/content/js/full-a.js:

$.post("/clippy/get?id="+

So I decided to try /clippy/get?id=1 and received:

"It looks like you're trying to reverse-engineer the clippycorn. You're not getting any help with that."

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Edit: I'm making some progress here - it seems that I need to make a POST request to the URL and pass along the fkey parameter. Doing this usually yields:

{
  "later": 1
}

...but every once in a while you'll get a different response. The response seems to be based on the id parameter. Here is the table of messages we have managed to construct so far:

• 1: {"text":"It looks like you're downvoting some posts. Do you need help?","thanks":"Continue downvoting without help","options":[{"text":"Look at funny cat pictures to lighten the mood","link":"http://google.com/search?tbm=isch&q=lolcat"}]}

• 2: {"text":"It looks like you're reading the FAQ. Would you like help?","thanks":"Read the FAQ without help","options":[{"text":"Read the FAQ about reading the FAQ","response":"I am sorry, there are no FAQFAQ at this time."}]}

• 3: {"text":"It looks like you're searching for something. Want some help?","thanks":"Continue searching without help","options":[{"text":"Read the advanced search tips","link":"/search"},{"text":"Search on all sites in the Stack Exchange network","link":"http://stackexchange.com/search"}]}

• 4: {"text":"It looks like you have undismissed notifications. Can I help you with that?","thanks":"Leave the notifications alone","options": [{"text":"Learn how to dismiss notification bars","response":"Click the \"x\" on the side of the notification bar to dismiss it.","thanks":"Thank you!"}]}

• 5: {"text":"It looks like you would love an answer to this question. Would you like help?","options":[{"text":"Offer a bounty on this question","click":".bounty-link"},{"text":"Learn more about bounties","link":"/faq#bounty"}]}

• 6: {"text":"You seem to use your global inbox a lot. Did you know you can check much older inbox items?","thanks":"The small list at the top of the page is just fine","options":[{"text":"Go to my inbox page","link":"http://stackexchange.com/users/YOUR_ACCOUNT_ID?tab=inbox"}]}

• 7: {"text":"It looks like you received a good answer here, have you considered accepting it?","thanks":"I know what it means to accept an answer","options":[{"text":"Learn more about accepting answers","link":"/faq#howtoask"}]}

• 8: {"text":"It looks like you came back after all! Welcome back.","thanks":"Thanks, great to be back","options":[]}

• 9: {"text":"It looks like you like this site. Would you like to learn more?","thanks":"Just continue browsing around","options":[{"text":"Log in or create an account","link":"/users/login"},{"text":"Learn what this site is all about","link":"/faq"},{"text":"Discover other sites on the Stack Exchange network","link":"http://stackexchange.com/sites"}]}

• 113: {"text":"It looks like you're mistaking me for a horse. Might I offer you some help?","thanks":"Continue without learning","options":[{"text":"Learn about the difference between ponies and unicorns","link":"https://i.sstatic.net/sQXLc.gif"}]}

• 294: {"text":"It looks like you're asking about me. That's nice.","thanks":"Go on with asking","options":[]}

• 6495: {"text":"It seems you're having trouble phrasing a good question title. Would you like some help?","thanks":"Continue asking without help","options":[{"text":"Learn about writing a good title","link":"http://meta.stackexchange.com/questions/10647/how-do-i-write-a-good-title"},{"text":"Get some tips on how to ask questions that get good answers","link":"/questions/how-to-ask"}]}

• 22017: {"text":"It looks like you're asking about regular expressions. Do you want me to help you?","options":[{"text":"Get help parsing HTML with a regular expression","link":"http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454"}]}

• 314159: {"text":"You might be spending a little too much time thinking about this prank. Would you like some help?","options":[{"text":"Yeah, I... I should answer some questions or something.","link":"http://stackoverflow.com/unanswered"}]}

• 378212: {"text":"You appear to be hungry. Can I help you?","thanks":"I am not hungry","options":[{"text":"Learn how to cook a fish in a dishwasher","link":"http://cooking.stackexchange.com/questions/4708/is-it-possible-to-cook-a-whole-fish-in-a-dishwasher"},{"text":"Find out if microwaving food is bad for you","link":"http://skeptics.stackexchange.com/questions/528/is-food-cooked-in-a-microwave-oven-harmful-for-the-health"}]}

The 15 above were discovered while the prank was active. After it was disabled Balpha provided the message of the only missing one:

• ???: {"text":"Looks like you @mentioned the post owner there. That's not necessary.","thanks":"Continue without help","options":[{"text":"Learn more about replying in comments","link":"/editing-help#comment-reply","dismiss":true},{"text":"Just tell me why the @mention was removed","response":"The post owner will always be notified of new comments, so you don't need to @mention their name.","thanks":"I see, thanks."}]}

According to balpha there were three additional user-specific messages included.

In addition to the triggers built-in to the client-side JavaScript, any ajax requests can return an X-Clippycorn header with one of these IDs to trigger a message. For example, if you're writing a post that seems to be about the joke itself, the background request to /posts/0/editor-heartbeat/ask will return the header X-Clippycorn:294.

Bonus: if you try an ID that is not used or is non-numeric, you receive one of the following HTTP status codes:

• 437 Only Chuck Norris Can Request This Resource
• 438 Only Chuck Norris And Jon Skeet Can Request This Resource
• 442 Not A Real Question
• 456 These Are Not The Unicorns You Are Looking For
• 463 Hax0r Detected
• 469 Status Declined
• 477 Pluralization Bug
• 480 Freehand Circle Expected
• 481 Not Enough jQuery

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Some more poking around revealed the following URLs:

• https://meta.stackoverflow.com/content/img/clippycorn1_frames.png
• https://meta.stackoverflow.com/content/img/clippycorn2_frames.png

I've created a fiddle for viewing the animations here: http://jsfiddle.net/george_edison/JkJxz/9/embedded/result/

The blue bullet () is embedded in the stylesheet.

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Part of the JS has been de-obfuscated here: http://pastebin.com/N47agZzm

Answer 2

The Clippycorn knows too much.

Answer 3

Well, I live in Portugal, so it's already April 1st here (it's now 1H42 AM here)... And I just got the "Clippy" April Fool's when doing a search for fgets "segmentation fault" in Stack Overflow! :)

Here's a screenshot for that epic moment.

Have fun! :)

Answer 4

Seen on physics meta, when I typed a title, Backspace'd most of it, and left it hanging for a second

That title is too short to be useful. Can you add some more detail? simultaenously popped up

Also:

No clue why this came up, I switched to a dormant Physics.SE tab and clippycorn popped up.