In some cases there are times when one needs to induce vomiting. For example, after a night of partying one may need to vomit so as not to be subject to alcohol poisoning or a very bad hangover. Here are four sure-fire ways to make yourself vomit when in need:
1. The finger-down-the-throat method - Take your index finger and shove it in toward the back of your mouth as far as possible. Once you have hit your gag reflex you should begin to vomit.
2. The baking soda method - Grab a box of Arm&Hammer and a teaspoon. Ingesting a teaspoon of baking soda is downright nasty (but not harmful), so it'll come back up - along with the contents of your stomach.
3. Drinking saline solution - Mix two tablespoons of table salt with a glass of lukewarm water and chug.
4. The feather method - It doesn't really matter HOW you get the feather (kill a bird, kinky sex shop, etc.), but using a feather to tickle your palate (found at the back of the roof of your mouth) will trigger your gag reflex. This is an ancient Roman method that is equal to method #1.
Thanks to liveforever for methods #3 and 4.