system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When I drop multiple ice cubes into a glass of coke at the same time, why does it fizz up?
gpt
The surface of the ice, when dry, is quite porous.  This provides millions of encapsulation points for bubbles to form. You'll note that ice used in fountain soft drinks is wet. This smooths the surface and reduces foaming.