  We consider planar maps with three boundaries, colloquially called pairs of
pants. In the case of bipartite maps with controlled face degrees, a simple
expression for their generating function was found by Eynard and proved
bijectively by Collet and Fusy. In this paper, we obtain an even simpler
formula for \emph{tight} pairs of pants, namely for maps whose boundaries have
minimal length in their homotopy class. We follow a bijective approach based on
the slice decomposition, which we extend by introducing new fundamental
building blocks called bigeodesic triangles and diangles, and by working on the
universal cover of the triply punctured sphere. We also discuss the statistics
of the lengths of minimal separating loops in (non necessarily tight) pairs of
pants and annuli, and their asymptotics in the large volume limit.
