generally, baby boomers tend to stray from modernised culture, and keep a romanticised view on how things should be. one might classify certain beliefs of theirs as fucking bullshit. when a baby boomer repeats said fucking bullshit, a common way to shut it down is with the phrase ok boomer.
boomer: there are so many more of those gays than when i was a kid. don’t you think it’s a bit much?
non-boomer: ok boomer
An ageist(yea that's a word) phrase used by younger generations to react to something said by someone born in between 1946 and 1964 when they are relating to when they were a kid.