Rotten Flesh

Rotten Flesh is a food item dropped by Zombies and Zombie Pigmen. Eating it restores 20% of your hunger meter. However, Rotten Flesh has an 80% chance of causing food poisoning. Once poisoned, you will notice that your hunger meter turns green and floating green bubbles will appear around you. You can cure your poisoning by drinking a bucket of milk. Rotten Flesh cannot be cooked and is not used in any crafting recipes. Rotten flesh heals Wolves without poisoning or causing damage to them.

Advantages

 * Rotten Flesh is rather easy to get once one has a sword/bow and armor, as zombies are more common than passive mobs
 * Rotten Flesh can be a good emergency food when other sources are depleted if used in high dosages, restoring more hunger than the poison can take away
 * Rotten Flesh may be used to feed and breed wolves rather than other meats as wolves do not have any hunger bar, so they are immune to food poisoning

Disadvantages

 * Rotten Flesh has a 80% chance to trigger food poisoning, making hunger deplete three times as fast for thirty seconds
 * Rotten Flesh only restores two hunger
 * Killing zombies for rotten flesh may be dangerous for under-equipped players
 * Rotten Flesh restores less saturation than other meats

Using Rotten Flesh in Battles
If you have 6-12 pieces of it in your hotbar, a good tactic is to dive behind cover and eat a piece of it when hungry, during a fight with Skeletons or other hostile mobs. Although it won't restore a substantial amount of hunger, it is a useful means of staying topped up (in order to keep your health regeneration going) while taking fire, which can keep you alive. As soon as you're out of the fight, however, you will likely want to eat a more substantial piece of food as soon as you get hungry again, because of food poisoning.

Trivia

 * Before rotten flesh was added, Zombies dropped feathers. This was because feathers were added before Chickens, and there was no other way to obtain feathers at that time.
 * In Alpha and Beta, Zombie Pigmen dropped Cooked Porkchops instead of rotten flesh and gold nuggets.
 * Since drinking milk stops all potion effects, one could use a cow and a bucket to eat rotten flesh without getting poisoned for 30 seconds.
 * Eating rotten flesh on peaceful mode, as of Minecraft version 1.2.5, will not cause food poisoning.
 * Rotten Flesh in the weekly snapshot 12w21a can be used to buy an Emerald.