The expression “and a no brainer” means “as clear as day, to everyone and everyone, ” but where it came from is not clear to everyone. The source of this phrase is considered the poem by V. V. Mayakovsky "The Tale of Petya, a Fat Child, and About Sim, Who Is Thin, " it contains the following lines: "Even a hedgehog is clear - this Petya was a bourgeois."
In 1958, the fathers of Soviet science fiction, the Strugatsky brothers, wrote the book "The Land of Crimson Clouds". The publication casually mentioned the famous expression of Mayakovsky. Since the Strugatskys were then read by everyone, young and old, the phrase quickly went to the people, becoming a stable expression.
According to another version, the origin of this phraseological unit is associated with education in the first Soviet boarding schools. In them, more capable adolescents were taught for 2 years (grades A, B, C, D, E), and the rest for 1 year (grades E, F, I). It was the students of one-year education who were called “hedgehogs”. The knowledge base of the two-year students was greater than that of the one-year students who only recently entered the boarding school. Therefore, pupils of 2 years of study, to define stupidity, used the expression "and EZHU is understandable", meaning pupils of one-year study.