My father liked to fish, often using worms as bait. He would go outside in summer, about an hour after sunset, to collect the nightcrawlers that came out looking for mates. I remember some fun evenings joining him to catch worms. Dad experimented with media to store the worms until he was ready to fish. He found that the best way to keep them alive was to put them in a can with topsoil and coffee grounds.
One recent morning I had to go out and do things without benefit of my morning coffee. I got to thinking about these worms and suddenly it hit me: Of course they were lively, from all that caffeine!