Once in the bloodstream, alcohol will run its unpredictable course of physical and psychological effects. Vomiting will remove the contents of the stomach. Only the vomitus is unavailable for absorption. Remember, alcohol is a drug. No one can afford to be confused about this.
Drug interactions can be lethal.
I'm over 21 and I've been asked to buy alcohol for 20 year-olds. These are my friends. Just say no. Buying alcohol for people under 21 is illegal. When I got to MIT, I stopped doing the hobbies I had at home and started into partying with my new friends.