The Old Days
It is commonly believed that a the vomitorium is an ante-room off the main banquet hall in a Roman home where the guests may relieve themselves of their stomach contents during orgies. This is incorrect. Roman nobles thought it the height of manners to simply lean over their lounge chairs and vomit on the floor. Others say that the vomitorium is the broad accessways out of the Colosseum and other Roman stadiums where the patrons could rapidly exit the buildings at the end of the event, hence be 'vomited' out into the streets.
In modern usage, Uncyclopedia is essentially a web enabled vomitorium. People gather in order to spew their worst ideas out upon the internet, and the admins take on the role of those who are puked upon and have to clean everything up.
Vomitoriums can be found nowadays in most popular bars, though the common people usually refer to them as toilets or sinks. Unfortunately, these vomitoriums are not as well kept as the vomitoriums of old, and sanitation has become a problem in recent years.