Chinese zombies

Chinese Zombies are the zombies found when you scroll way down to the bottom of the Achievements screen on the DS/DSi, iPod Touch/iPhone/iPad, Android, Windows Phone 7 and PC Game of the Year versions of Plants vs. Zombies. To access it, you keep digging deeper and deeper, past a pipe, Lex and a Zombie Worm, gems, (and, in the iPad and DS version, Baron Digo and a Chuzzle, and in the PC and iPod Touch/iPhone versions, a pipe and from another PopCap game), and Bjorn's skeleton until you reach it. Zombie China is upside-down, as it is on the opposite side of Earth.

iPod Touch/iPhone
On the iPhone/iPod Touch version, Chinese Zombies are some Zombies in traditional Chinese clothing in what appears to be the Yuyuan Garden of Shanghai, China. To be more accurate, it's the Huxin Ting (Mid-Lake Pavilion) in Yuyuan Also, the Noodlehead Zombie is not present.

iPad, DSi and DS
The iPad, DSi and DS Chinese Zombies are very similar to the iPhone/iPod Touch versions, but it includes another zombie with chopsticks and a takeout container on his head with Brains. There are noodles hanging from the takeout container. Also, the Chinese building is more in the distance and less colored, and there are clouds surrounding the Chinese Zombies. On the iPad and iPod Touch, scrolling down to Zombie China earns you the achievement Down the Hole!.

PC and Mac
Chinese Zombies are only accessible in the GOTY, which can be reached by scrolling down on the Achievements screen. You'll see Lex (a character in Bookworm) and a zombie worm, then some gems, then a Chuzzle, then a dead version of Bjorn, a blue peg and an orange peg, a pipe, and finally Baron Digo and some Zuma balls before reaching Zombie China. Peking Express and Down in the Hole! cannot be achieved on this version.

Xbox 360/PS3
Although Chinese Zombies are not in the Xbox Live Arcade or PlayStation Network version of the game, going to the Leaderboards and then selecting the Survival: Endless option, Lex, the fossil, and gems can be found by scrolling down farther. The pattern continues until the very end.

Down the Hole! and Peking Express
These two achievements happen when you visit Zombie China. It is one of the easiest achievements in the game. It is only found on the games that involve having to scroll down. When you achieve it, it records your record and you can try to break it.

Trivia

 * The Chinese Zombies are possibly based on Jiang Shi (僵尸/殭屍, stiff corpse), a type of Chinese zombies.
 * Going to China in the Acheivements section is a reference to the "dug all the way to China" joke.
 * Contrary to popular belief, you can not actually dig down straight to China, as, even if you could somehow could break through bedrock and other minerals, you would still hit the Earth's core and die a fiery death.