trip down the rabbit hole 

Taking drugs such as LSD to experience an Alice and Wonderland like adventure

Dude we are going to take a trip down the rabbit hole tonight.

trip down the rabbit hole by Heasdhe May 8, 2015

"Go down the rabbit hole" 

The process by which a sex partner, presumably a male, inserts an object into the anus without permission.

While doing Jennifer doggy stile, Joey attempted to "go down the rabbit hole", much to Jennifer's chagrin.

"Go down the rabbit hole" by Gerald Dickens November 19, 2007

chasing the rabbit down the hole 

Something that is very common to observe Mensa (high IQ) members doing when discussing a topic. They'll start off on one topic, but will usually veer off topic several times in rapid succession and end up talking about something totally different than when they started. This can happen within first few minutes of the discussion.

Damn! John is chasing the rabbit down the hole again!

chasing the rabbit down the hole by Yepes July 6, 2017