The flehman response also known by some people as 'stinking face' it is actually called the flehmen response. In German, the word flehmen means lip curl or curl of the upper lip. A tiger opens wide to allow the scent to reach the roof of its mouth where the Jacobson organ is located.
The Jacobson organ is important for mating, marking territory, and intraspecific communication. Tigers use the flehmen response when investigating different scents left by other tigers. It’s like smelling in high definition.