In your face
In a bold aggressive manner.
This originated in the US in the 1970s. Many of the earliest citations relate to confrontations in sport. The earliest I can find is from Charles Rosen's novel about basketball - A Mile Above the
'Stuffed!' shouted the taller boy. 'Doobie got himself stuffed!... In yo' face, Doobie!'
More recently the phrase has often been used to describe the nose-to-nose pre-fight confrontations between boxers.