Metal Gear Solid 4: Guns of the Patriots Easter eggs

Vomiting Snake
If you kill a large enough number of enemies in a conflict zone, you will hear Liquid from Metal Gear Solid say "You enjoy all the killing, that's why!", and Snake will vomit. Note: You can delay the vomiting by hugging the wall. The next time you kill someone, however, it will happen again until you finally vomit.