Metal Gear Solid 3: Snake Eater HD Edition Tips

Make Eva vomit
Similar to making Snake spew, when you're escorting Eva to the lake, go into the cure option in the Survival Viewer to look at Eva and then use the analog sticks to spin her around several times. When you resume gameplay, Eva will vomit. Repeat this enough times and she will complain about stomach cramps and say other funny comments but this will also diminish her stamina quicker.