Easter egg hunt: Seven secrets of the world wide web

There are many hidden secrets tucked away in the media we consume, placed there by mischievous - or perhaps just bored - programmers and developers.

They're known as "Easter eggs" - and the web has them in abundance.

Andy Clarke, who owns Wales-based web design studio Stuff & Nonsense, has his own simple definition: "It's something unexpected that makes you smile."

"It's fun to slip these things in and wonder if people will notice them, and how long it will take," he tells the BBC, remembering one of his own eggs, in which users could shoot a beloved mascot on a local council's website. They never found out.

So here, in no particular order, are some of the best website-based Easter eggs the BBC has found out there. There are no doubt thousands more. You can tweet your favourites to us on @BBCTech.

Please note - all of these worked at the time of publication, but developers have a tendency to remove Easter eggs when updating websites and software. Don't write in.

It's a combination of actions that is etched into the brains of gamers everywhere - the Konami code.

Up up, down down, left, right, left, right, b, a.

Used to unlock cheats on many classic games made by Konami - and others that aren't - the cheat code is also now used as a common way to enable Easter eggs.

Using your keyboard's arrow keys, tap in the sequence on Digg.com for a musical treat.

Or, even better, give it a go on both Vogue.com and GQ.com to meet the internet's most fashionable dinosaurs.

If you're feeling especially brave - try it on Buzzfeed.com for a terrifying glimpse of what entertainment news may become if the world doesn't stage some kind of intervention.

Diving into Google's vast library of street level imagery around the world is entertaining in its own right, but it gets even more interesting when you're taken to a different dimension altogether.

Situated just outside Earls Court station on the London Underground is the Tardis from Doctor Who. A quick click on the double arrows will bring you inside for a nose about.

Elsewhere on Street View, meet the Google team that made it, having a song and dance outside the company's headquarters.

And for another fantasy fiction twist, use the "directions" function on Google Maps to get instructions to walk from "The Shire" to "Mordor" - and receive some cautionary advice.

Not content with producing real Easter eggs of the edible kind, stashed away on various Nestle-owned sites are some creative renditions of their most famous brands' logos.

By viewing the source code (right click "view source" or "view page source" on most browsers) of kitkat.com, or Skittles.com, you'll see some artistic text art placed in amongst the page's code.

YouTube, like other Google products, is full of Easter eggs.

For a while, the classic game of Snake could be launched by pressing up and left on the keyboard while a clip was buffering. Sadly, that doesn't appear to work anymore. But in its place, a game of missile command can be launched by clicking to the right of a video and typing "1980" on your keyboard's number pad.

While you're on YouTube - try out searching for "do the Harlem shake" and "doge meme".

This list of Easter eggs is here to demonstrate that these odd features exist. What it isn't designed to do is explain why. Which is good - as the pointlessness of this next trick would leave us empty-handed when looking for an explanation.

Once logged into Facebook, head over to your settings section. Change your language, and choose "English (upside down)", and there we have it. Upside down text everywhere.

While you're at it, pirate mode is fun - turning the "Like" button into the far more satisfying "Arr!".

The BBC would never condone sports betting while at work, but if you were unfortunate to be doing such an activity and a superior appeared behind you at a moment's notice - the web team at Sky Bet have something of an answer.

By clicking the small icon above the Facebook share button the upper-right-hand-side of the page, a very dull screen with spreadsheets appears, proving your innocence. Until next time.

Typing various phrases into Google can produce some interesting results.

First, try "do a barrel roll". Then how about "askew".

On Google Images, a search for "Atari Breakout" will steal a lot of the working day. As will a regular search for "Zerg Rush".

There's a full list of Google Easter eggs on a dedicated Wikipedia page.

Follow Dave Lee on Twitter @DaveLeeBBC