If not exactly "pretty," he probably will be wearing rose colored vestments. The third Sunday of Advent is Gaudete Sunday, so called from the first word of the Introit at Mass (Gaudete, i.e. Rejoice). This is our sign that Advent is almost over and we may look forward with greater joy than ever to the Lord's coming as there will be only one more Sunday in Advent ... and then it will be Christmas!
Read more at New Advent.