ya I can vomit on demand. without even gagging myself using fingers. just use my tongue. so PE in sch last time was slack one corner all the way unless it's "soccer" day..
actually it's most useful when :
1) hawker/restaurant give you attitude problem and refuse to replace your crappy cold food. create a "food poisoning" scenario
2) you chope 3 seats for your friends who're on their way. and some stubborn idiot just sits down despite telling him/her "the seat is taken" . so the best shot is to puke onspot and spoil their appetite without starting a fight or use cuss words.