Boomer
boomer; an out-of-touch older person (mocking, from 'OK Boomer')
Origin
Short for 'Babyboomer', i.e. a person from the high-birth-rate postwar generations. In youth slang 'Boomer' is used mockingly and pejoratively for older people with views felt to be out-of-touch or conservative. The term gained popularity through the internet phrase 'OK Boomer', with which younger generations brush off lecturing or backward comments from older people.
Examples
Versteh ich nicht, sagt der Boomer.
I don't get it, says the boomer.