Wow! I was going to have to go looking for that thread TheMetal1 quoted above or else rewrite it. That came in handy, TheMetal! Thanks.

Yep, it just seems like for a very small fraction of people, the nausea/vomiting centers of the brain get stimulated instead of subdued by cannabis. I also think sometimes a very dramatic vomiting response may have more to do with anxiety--panic and an adrenaline surge frequently spur vomiting, too--or even a response to coughing from the harshness of the smoke.