I've heard that people use dry ice with drinks, but I'm wondering how safe that is. Since dry ice is carbon dioxide, isn't that dangerous?
In addition to the extreme cold of dry ice when it warms and becomes a gas again it gains volume rapidly. If it is in your stomach you will inflate to fatal levels. There are many cases where this has happened. If you are drinking a beverage with dry ice in it make sure it has all evaporated (melted). It is used because of the 'cool' steam it gives of as it heats.
The volume increase with sublimation is the same as liquid nitrogen: