Green’s Dictionary of Slang

bummer n.4

1. (drugs, also bummer trip) an unpleasant drug experience, esp. while using LSD or any other hallucinogenic.

[US]T. Wolfe Electric Kool-Aid Acid Test (1969) 45: He and Lovel had tried the whole range of the drugs, LSD, psilocybin, mescaline [...] Ditran the bummer, morning-glory seeds.
[US]Science News 17 Apr. 264: The worst bummer of all time was recorded by Robert Louis Stevenson. It seems that the good Dr. Jekyll tripped out on a mysterious powder and ended up as the nefarious Mr. Hyde.
[NZ]H. Beaton Outside In I ii: We’ve had some bummers on peroxide.
[US]ONDCP Street Terms 4: Bummer trip — Unsettling and threatening experience from PCP intoxication.

2. any unpleasant experience, depressing circumstances.

[US]H.S. Thompson Hell’s Angels (1967) 95: Man, it was a bummer, it wasn’t right.
[US]J. Thompson ‘Sunrise at Midnight’ in Fireworks (1988) 178: Let me tell you why the joint is really a bummer.
[WI]M. Thelwell Harder They Come 322: Oh gross — what a bummer.
[Aus]R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 206: So the big night was a bit of a bummer.
[US]T. Jones Pugilist at Rest 125: The whole idea of labor and childbirth sounds like a total bummer.
[Aus](con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 61: ‘I don’t really want to get into another duo. The last one turned out to be a bit of a bummer’.
[Aus]R.G. Barrett Leaving Bondi (2013) [ebook] ‘It’s [i.e. a movie shoot] turned out a complete bummer’.
[UK]Observer Mag. 27 Oct. 42: That’s a bummer, as I now have to be careful about skin cancers.
[US]E. Weiner Big Boat to Bye-Bye 177: Stephanie remained deadpan as she said, ‘Bummer’.
[US](con. 1973) C. Stella Johnny Porno 221: She pouted as she withdrew her leg from his lap. ‘Bummer,’ she said.
[Aus]N. Cummins Adventures of the Honey Badger [ebook] What a bummer! From penthouse to shithouse in one easy lesson.
[Aus]G. Disher Consolation 299: It was a bummer [...] that Cater still hadn’t admitted, in front of witnesses, to being at Maggie Groote’s house.
[Ire]P Howard Braywatch 202: I’m like, ‘That’s a bummer’.

3. a person whose conduct can ruin the enjoyment of a drug.

[US]G. Shelton ‘Fabulous Furry Freak Bros.’ [comic strip] Quit bringing us down, man! You’re a real bummer!
[US](con. 1970) J.M. Del Vecchio 13th Valley (1983) 109: These dudes up here are really into their dope. Don’t be a bummer. Okay?

4. (US campus) a hard examination.

[US]Baker et al. CUSS.
[US]Eble Campus Sl. Mar. 2: bummer – [...] a bad deal: That test was a bummer!

5. a failure or bad idea.

[US]New Yorker 3 Oct. 76: All the films released this summer have been box-office bummers.
[UK]K. Waterhouse Soho 202: If the idea was such a bummer [...] would the Arts Council cough up twelve and a half grand?

In phrases

ride a bummer (v.) [orig. Hell’s Angels use for a bad crash, see Tom Wolfe The Electric Kool-Aid Acid Test (1968): ‘Bummer was the Angels’ term for a bad trip on a motorcycle and very quickly it became the hip world’s term for a bad trip on LSD’; note 19C racing jargon bummer, a bad gambling loss]

to be depressed.

[US]Eble Campus Sl. Mar. 8: ride a bummer – be depressed.