Describes mostly older generations (boomers and older) who have difficulties adapting to modern society with its changing values, new technology and younger generations.
While boomers still tend to name millennials "generation Y" (modest reference to themselves), millennials fought back, and renamed the older generations.
It refers to a parable about the difference between the generations: "While we millennials and younger build real houses, they boomers and older still build theirs with corrugated sheets only."