What is the meaning of the phrase “in all seriousness”?
According to one version, it originally had a different meaning. When they said "во все тяжкие" (“vo vse tyazhkye”) or “in all seriousness”, they meant... the ringing of bells! In the book that describes the order of Orthodox worship - ‘Typikon’ - it is mentioned that the para-ecclesiarch, the church servant who rings the bells, on Holy Saturday, strikes “in grave and great”. That is, to the largest bells.
But there is a more prosaic explanation. In Vladimir Dahl's explanatory dictionary of the Russian language, there is an expression, “pustitsya vo vse nelegkie” (“to go all out”), in other words - into a dissolute life. And “tyazhkye” began to be used as a synonym. By the way, the title of the hit TV show ‘Breaking Bad’ was named ‘Vo vse tyazhkye’ for Russian audiences.