Blowing ectoplasm bubbles
When I attended the University of Waterloo, I lived with a bunch of geeks and one token arts major. Ross was an English major via Urban Planning and was the perfect yin to our yang, as it were.
One year for Christmas I got him a tub of Ghostbusters ectoplasm ... a container of viscous purple goo. It would spread out to about the size of a garbage can lid on the kitchen table.
Somehow Ross and I discovered that by sliding a straw under the flat disc of goo, we could blow enormous purple bubbles! With care and proper technique, a head-sized bubble could be achieved before the inevitable weak spot gave way.
This activity also caused much laughter of the I'm-still-awake-at-3am kind. Which, over time, caused us to inhale quite a bit of ectoplasm.
When I die, the autopsy will show fluorescent purple lungs.