A frightening or depressing drug experience, esp a nightmarish time with LSD (1960s+ Narcotics)
Any unpleasant occasion or experience; bummer, downer: The party was a real bad trip(1960s+ Counterculture)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with bad trip
A frightening or otherwise very unpleasant experience, as in Given the poor turnout, her book tour was a bad trip. The term comes from drug slang of the mid-1900s, where it meant experiencing hallucinations, pain, or other terrible effects from taking a drug, especially LSD. It was then extended to any extremely unpleasant experience.