rabbit hole
A situation, journey, or process that is particularly strange, problematic, difficult, complex, or chaotic, especially one that becomes increasingly so as it develops or unfolds. An allusion to Alice's Adventures in Wonderland by Lewis Carroll, it is used especially in the phrase "(go) down the rabbit hole." Overhauling the current tax legislation is a rabbit hole I don't think this administration should go down at this point. I've stayed away from drugs and alcohol since coming to college. I have an addictive personality, so I decided to just avoid that rabbit hole altogether.