I don't have a lump but I am curios all the things I could do with one if I bought some.
Impress people by breaking it in two with your head (I did) L
use it to keep your beer cool. (seems pretty obvious to me)
Risking shameless self promotion,https://www.instructables.com/id/How-to-easily-remove-vinyl-tiles/
I've recommended this to a non-instructables using friend. Good work.
Let me know how it goes for them. I'm interested in feedback.
There are lots of examples online if you search, just remember in most places you have to be the age of majority (adult) to purchase it, because it can be used for evil as well as good.
put your tongue on it. 8^)
Besides cooling things down, try some of the things here:http://www.west.net/~science/co2.htm And type in the words, "experiments with dry ice" in Google for a lot of other 'cool' ideas.