The Brief: "Boomer" is shorthand for a member of the Baby Boomer generation. "Boomers" can be a slang term for psychoactive mushrooms.

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A Boomer is someone who was born approximately between 1946 and 1964. The term “boomer,” has become an insult among millennials and Gen Zers as in “Ok Boomer.”Β
The most devastating put-downs, 2019 edition:
Ya basic
Ok Boomer
I bet you liked the GOT Finale— Emily Andras (@emtothea) October 30, 2019
Similar to shrooms and gooms, “boomers” can also refer to hallucinogenic mushrooms.
So I posted a pic of some dank morel mushrooms on insta and somebody legit messaged me & asked if they were boomers lolol
— conorfortyhandz (@trvphippie) August 8, 2018