How do you say boomer in Japanese?

There isn't a direct equivalent of "boomer" in Japanese that carries the same cultural baggage and slightly derogatory connotation. The word "boomer" is very specific to internet culture and generational conflict in English-speaking countries.

To convey the meaning, you'd need to use a descriptive phrase depending on the context:

* If referring to the Baby Boomer generation: ベイビーブーマー (beibībūmā) is a direct loanword and perfectly acceptable.

* If using it in the derogatory sense: You'd need to describe the behavior or attitude you associate with the term, rather than using a single word. For example, you could use phrases like:

* 古臭い (furukusai) - old-fashioned, outdated

* 時代遅れ (jidai okure) - behind the times

* 保守的な (hoshu teki na) - conservative

* 頑固な (ganko na) - stubborn

The best approach depends heavily on the situation and what aspect of "boomer" you want to emphasize. Simply using ベイビーブーマー (beibībūmā) without further context might not convey the intended meaning if you're aiming for the negative connotation.