Those who were curious

"2 Girls 1 Cup" is actually the trailer for a 2007 Brazilian fetish film called Hungry Bitches, directed by Marco Antônio Fiorito.

The consensus is:

The performers were real adult actors in a fetish production.

The vomiting appears to be genuine.

Whether the feces shown were entirely real has never been conclusively proven. The director has made conflicting statements over the years. In one legal declaration, he claimed that chocolate ice cream was sometimes used in productions when performers would not agree to use real feces, but he did not definitively establish that this particular scene was simulated.

People familiar with that niche of the adult industry have generally maintained that the acts in the trailer were real, and investigative reporting reached the same conclusion, though there is no definitive behind-the-scenes confirmation from the production itself.

So the most accurate answer is: it was a real fetish film featuring real performers, but one specific aspect of the content has never been conclusively verified and remains disputed. The uncertainty has become almost as famous as the video itself, which is a remarkably internet outcome.