We know he dresses well, but can he act?

How I Met Your Mother will find out on the show's 100th episode, when Tim Gunn guest stars on the special half hour.

As first reported by Mo Ryan of The Chicago Tribune, the Project Runway host Gunn will help Barney (Neil Patrick Harris) resolve a serious sartorial crisis during the installment.

Of course, Gunn will be overshadowed during this episode. Rachel Bilson will also guest star, and rumors are swirling that she may actually be the famous mother in question!

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.