Until very, very recently, adult themes like nudity and alcohol abuse were a huge no-no in most video games... which is probably why game designers spent so much time hiding those things. And yet we found them anyway.
From kiddie characters getting plastered to secret and unpleasant hidden nudity, the inappropriate stuff sometimes came in the form of Easter eggs, or glitches, or censored scenes only found in certain versions of the game, but it was there all along. Oh, it was there. Where? Glad you asked.
1) Vendetta (Arcade) - The Most Offensive Enemy Ever
This classic arcade beat 'em up had a censored level that started pretty normally... until two half-naked biker dudes wander in and start humping you to death. You, and anything that crosses their path. In fact, one of them humps a lamppost so hard that the light bulb falls down and kills him. Meanwhile, the other people in the street just watch. They... they just watch. OK, we can see why they omitted this part of the game outside Japan.
Of course, you can hit them back, but that's almost as bad: When you knock them out they cover their genitals (even if you punched them nowhere near the groin area), and they fall on the floor with their butts suggestively raised up. Do not, for the love of all that is holy, let them put you on the ground. Just trust us on that one.
This is punishment for all those times we tried to look up Chun-Li's skirt, isn't it?
2) Kirby's Dream Land 2 (Game Boy) - Kirby's Dream Lady
The first Kirby game for Game Boy had a hidden vertical room where you scroll past a very suspicious series of blocks, each shaped like a different part of the female anatomy... including the nipples, the belly button, and the conveniently-placed fuzzy enemy in the crotch. Considering that this game is set in Dream Land, this probably means Kirby woke up all sticky.
In other words, while you thought you were playing an innocent Kirby game, you were actually "exploring" some lady's body. At least it doesn't look like she minds it, judging by that happy face.
3) Rings of Power (Sega Genesis) - Breasts of Power
This complete Lord of the Rings rip-off by the creators of Crash Bandicoot and the Uncharted series would be totally forgettable if it didn't have a secret code for 1991-era graphically represented boobs.
Typically, the fully-clothed model in Naughty Dog's logo was only seen for a second upon booting up the game, but if you plug a controller into port two and simultaneously hold down/right on the d-pad and the A, B, C, and start buttons, you see a lot more of her. Meaning her boobs.
Since the game is absolutely terrible, this is quite literally the only reason anyone still knows what Rings of Power is.
4) Wild Woody (Sega CD) - The Little Mermaid Just Got Real
Although the name makes it sound like exactly the kind of game that would have a dirty Easter egg, Wild Woody is actually a bog-standard kids' platformer game starring a pencil. It, too, would be completely forgotten (though it's more likely no one even knew about it in the first place), if not for extremely well-hidden cartoon nudity.
Using a convoluted series of steps, you can access the game's debug mode and pick up items hidden in the walls all over the Pirate World Act II stage. You actually have to collect the items in a specific order (which you can find in this video) without accidentally picking up anything else.
It's a really huge pain in the ass, but the payoff (if it even counts as payoff in the world of on-demand internet porn) is good old 16-bit bare mermaid breasts.
5) The Apprentice (Philips CD-i) - What Hogwarts Would Be Like in Real Life
A dumb platformer for Philips' one and only (and terrible) foray into gaming, the CD-i, The Apprentice didn't turn many heads. Since approximately four and a quarter people actually owned a CD-i (and they were all too busy weeping quietly because they got fooled into buying the various Legend of Zelda games for the system), few people have even heard of the game, much less played it. That's probably how they got away with hiding full-frontal female nudity in it.
On the game over screen, the player can input various short codes that change the original animation into Mortal Kombat parodies, including five different "Nudality" scenes featuring the main character magically undressing creepy, child-like anime girls.
6) The Legend of Zelda: Link's Awakening (Game Boy) - Link, the Hero of Voyeurism
Link's Awakening was the first portable game in the Zelda series, and also the one that established that Link is a pervert. Or at least he was in the Japanese version (in the American one he was merely a dirty thief).
At one point in the game, you can peek at a busty hippopotamus lady as she poses naked for an alligator painter (as in, an alligator who paints, not a guy who paints alligators). She quickly covers her bosom and yells at Link to get out, but Koholint Island is full of opportunities for the enterprising voyeur: You also meet a mermaid who lost her bikini top and can dive underwater to peek at her goods, at which point she calls you a pervert and swims away. Naturally, both of these scenes were censored in the American version (they changed the mermaid's missing bikini top for a necklace and the hippo's boobs for a tragically flat chest).
7) Grand Theft Auto 3 (Playstation 2) - Grand Dick Notepad
The first PS2 Grand Theft Auto game included an easy-to-miss (but difficult to forget) Easter egg. Random pedestrians holding yellow legal pads could occasionally be seen wandering around Liberty City.
If you actually took the time to look at their handiwork, you'd find the above-- a cartoonish dick, complete with, uh, fluid coming out. Dealer's choice on what kind of fluid it is.
8) Rampage: World Tour (Multiplatform) - Pixelated Privates
Rampage: World Tour, the 1997 sequel/reboot to the 1986 arcade game Rampage, brought back an old animation with something a little extra on the side. (That something being genitals.)
Just like in the original game, when your building-crushing irradiated giant has all of its health knocked out, they shrink back down to their human forms. In versions of the game with higher graphic quality (i.e., not the Game Boy one), the art people apparently decided to throw in split second full-frontal nudity for both the male and female characters. Just look at those sexy pixels.