Following Williams' announcement, Dunkin' will be giving away a free Ol' Roy Donut with the purchase of any beverage only on Saturday, April 3.
The donut itself is filled with custard and topped with chocolate icing and Carolina blue drizzle.
The special will be available to all Dunkin' locations in North Carolina.
UNC men's basketball coach Roy Williams announced his retirement Thursday, Apr. 1, after 33 seasons as a head coach in the NCAA.
Williams led the Tar Heels to three national championships. He finished his career, at age 70, as the third-winningest coach in Division 1 history.