A cool thing to do if you have leftover dry ice is to snuff out candles using just carbon dioxide.

You put dry ice in a jar and let it sublimate. The carbon dioxide will remain in the jug, as the density of CO2 is around 1.98 kg/m3, making it denser than the average density of air, which is 1.225 kg/m3.

So, you can literally pour carbon dioxide out of the jug and snuff out a candle by removing the oxygen from around the flame.