Easter eggs are a much-loved tradition in gaming, in which cheeky developers leave behind carefully hidden in-jokes in their games and the player, upon finding them, feels like they're in on the gag.
Sometimes they're subtle nods to other games and the like - the odd Portal sign on a wall, a Mario pipe hidden in a room, that sort of thing. Our favourites are the less sensible examples that make you wonder which nutter on the development team came up with the idea - and how he got it into the final product.
We've gathered 50 of our favourite weird gaming Easter eggs, along with instructions on how to find each of them in case you want to show off to your friends, family or loved ones. They'll think you're brilliant, honest.
Did we miss your favourite? Let us know in the comments below.
1) Dead Space 2 - Hand Cannon
When you finish the game on the Hardcore difficulty setting, start a New Game+ and head to a shop. You'll be able to get the Hand Cannon, a big foam hand with unlimited ammo that Isaac has to shout "pew pew" to shoot.
2) Fallout: New Vegas - Indiana Jones' remains
You need to have chosen the Wild Wasteland trait at the start of the game for this one. Slightly southeast of Goodsprings, follow the road out of town and you'll see a refrigerator containing a skeleton and a hat. This is a reference to the ridiculous scene in Indiana Jones And The Kingdom Of The Crystal Skull, where Indy survives a nuclear bomb by hiding in a fridge.
3) Gears Of War 2 - Cowboy hats
Start Chapter 3 of Act 1 on Insane difficulty and shoot the three cowboy hats (as shown in the video above). You'll need to press the Back button to stop Marcus talking on his headset to give you time to shoot. Shoot all three and the team will all put on cowboy hats.
4) Crackdown 2 - Giant toilet
Play through the game until the Agency Tower reaches the maximum height possible. Climb to the top of it (or fly to the top in a helicopter) and jump off into the nearby chimney stack (see its location in the video above). If you manage to drop through the chimney without taking damage you'll land in a massive toilet (and unlock the 'Pebble Dash' achievement).
5) Portal 2 - Singing turrets
Blow up the turret behind the grate in Chapter 3 and walk through the gap it makes to find this quartet of singing turrets.
6) Diablo II - Cow level
After beating Diablo, start a new game with the same difficulty. Using the Waypoint system, portal back to the Rogue Encampment in Act I. Place a Tome of Town Portal and Wirt's PegLeg in the Horadric Cube and transmute. A portal will be opened, which will lead you to the Cow level.
7) Crysis 2 - Disco elevator
Take the elevator down to the end of the Dead Man Walking level and go down the hallway. Go right and look for a security camera. Hop the red rope and look for a switch. Activate the switch and a red light will shine. Head back to the elevator and hop another red rope to reach a second elevator. The switch will be glowing. Hit it for a disco party.
8) Skate 3 - Isaac Clarke
To play as the hero of the Dead Space games, go to the cheat code menu and enter 'deadspacetoo'. You'll then unlock Isaac as a playable character.
9) GTA IV - The heart of Liberty City
Get inside the Statue Of Liberty and climb up the massive ladder inside it to find that it has an actual human heart. Which is a bit odd.