In continue to the definition by Spiel Brickner, which was rather accurate, I'd like to add a couple of things.While using the word " blyat " as a link word (regardless to its meaning) , there are no rules for where to place this word in the sentence . You may place it anywhere in the sentence as many times as possible, even after each word if you will, and it will still remain correct russian grammar.The bets anology demonstrating it, is the hebrew word "keilu", which northern Israeli bitches use similary as a link word placing it randomly in the sentence regardless the meaning of the word itself.