(n) When you start looking something up on wikipedia (usually something meaningful for a class or work) and end up clicking link after link of related topics in each article, until you've ended up on something completely unrelated and wasted a large amount of time on information you forget 1 hour later.

Running for exercise and picking up trash you find along the way. It's good for the body, mind, soul, and environment! Started in Sweden but is making its way to the U. S.