Smirnoff Ice is just kind of gross and unpalatable in general. Like to the point where “icing” someone is a frat-tier prank where you hide one and whoever finds it has to drink it.

As an “alchopop” I don’t think it has enough to mess with the stomach like that, although alcohol can be very variable in how it impacts you (my body just rejects straight liquor, I get drunk quicker on beer). Might have been the Smirnoff, might have just been your stomach getting upset for no reason (this will happen as you get older with or without alcohol, although obviously alcohol makes it much worse)