Jesse Tyler Ferguson guest judges on "Project Runway" with a Tie the Knot challenge that inspires a designer to propose to his partner

Jesse Tyler Ferguson appears as the guest judge on this week's Project Runway and challenges the designers to create unique looks with Tie the Knot bowties. Tie the Knot, in partnership with The Tie Bar, produces collections of unique bowties in limited quantities with the proceeds benefitting various organizations working for marriage equality for same-sex couples. Creators Jesse Tyler Ferguson and Justin Mikita were recently married in New York City.

The challenge so inspires one of the designers that he proposes to his partner of 18 years during the runway judging ceremony. Check out a sneak peek below and don't miss Project Runway on Lifetime this Thursday at 9 pm.