-3 points
Probably the sugar. Sugar decarbonates coke (and other sodas) pretty quickly. Add to that a container under pressure with only a small hole and you get an explosive reaction.
4 points
1 point
Yeah, but it works. When she was little, my sister did it all the time because she loved soda, but only without the carbon.
1 point
"The eruption is caused by a physical reaction, rather than any chemical reaction. " https://en.m.wikipedia.org/wiki/Soda_geyser
1 point