1) What someone says when they get unintentionally sidetracked from an intended goal or routine, due to being absorbed by matters that arouse interest, seem unusual and/or puzzling. This is different from being distracted, as while distraction is simply a means to an end,
going down a rabbit hole implies there is more than what meets the eye. Sometimes,
the rabbit hole may end up opening new journeys, which in turn opens even more journeys and so on. The rabbit hole can regard trivial as well as serious matters. This term has been used for very long (circa AiW), however, it has gained more notable usage in recent times due to digital media, perhaps a bit too much usage. It is also the plot for many action thriller movies.
2) Another term for taking
psychedelic drugs, especially when used as a euphemism.
1) John
accidentally bumped into a guy and a business card fell out. He picked it up and—when boredom stuck him—typed in the URL on the card. It brought him to a website that offered a lucid dreaming service, something he was never aware of. Soon enough, he went down
the rabbit hole and found more similar services. But that didn't end there, he found out that the technology could be altered to connect users to a dream. It still didn't end though, as John finally came into realization that he was dealing with the black market.
2) Guy 1: Hey, what's Greg doing today?
Guy 2: I heard he's going down
the rabbit hole
Guy 1: Oh, well let's better go tripsit him.