The animosity between Boomers and Millennials, both now long dead, became legend. Then one scholar noticed that all the Boomers were born before 1965, and all the Millennials after 1985.
One researcher suggested that no one was born in the intervening 20 years. Another thought that they all died in early childhood.
A user in a forum posited a missing, undocumented generation, and gave them the standard letter for the unknown, X.
They were laughed out of town.