Oh, the gravity bong. I was happy when I found out it had a name. My friends and I used to call it the "big bucket", since it really was a big bucket filled with water. Smoking was fun, it made everything look more interesting. We were a bunch of mathematicians and physicists doing experiments with ourselves, it was really fun. 1 or 2 of us eventually became sort of "addicted", but nothing too serious that could lead to a disaster.
For me... I think Bassdrop listed all of my reasons.