When you drink SN, all of the amount in your stomach is not instantaneously absorbed into your system. It takes some amount of time. If you vomit it out before it's all fully absorbed, then you haven't absorbed the full amount. Hence, the second glass. If you vomit that one up before all, or near all, of it gets absorbed, hence, the third glass. If order for SN to be successful (killing yourself), you need to absorb into your system the proper amount. An antiemetic is meant to alleviate the vomiting. Sometimes it works, sometimes it doesn't. SN will kill you if you consume the proper amount AND the proper amount is absorbed into your system.