Phrase used exclusively in CS:GO by angry russians forgetting all sense of logic and stop thinking straight

It's an expression used as a callout/strategy planning in CS:GO. It's commonly used in de_dust 2, a map from the aforementioned game.

B in "rush b" is a bomb plant spot, an objective in the game.

It's a phrase in it of itself.

Rush B is a common term used in the game 'CS:GO' to direct your teammates into defeat and mental depression; the 'Cyka blyat' which followed is mainly used in Russia as greetings and pleadings.