Stinky the Snail is a purchasable item found in all versions of Plants vs. Zombies that have the Zen Garden. He is available for purchase at Crazy Dave's Twiddydinkies for $3,000 after the Zen Garden is unlocked. He will slowly collect coins in the main Zen Garden area if he is awake. He stays awake for three minutes before collapsing in a deep sleep again, requiring manual prodding to reawaken. He has a sweet tooth for chocolate, a substance dropped by various zombies. Feeding Stinky a piece of chocolate will cause him to accelerate considerably and stay awake for an hour. In the iPad and iPhone versions of Plants vs. Zombies, Stinky will continue to collect coins after the Zen Garden is closed if fed chocolate. In the iOS versions of the game, Stinky will collect money while the player is away, but in other versions it won't do this.
Although Stinky needs some time to reach the coins and collect them, if you quit your main Zen Garden (or going to the Mushroom or Aquarium Garden) with lots of money not collected then open the main Zen Garden again, Stinky will collect all of them. (iOS and Android only)