Potbelly, the sandwich shop, is putting the whirled in the World Meeting of Families.

Schoolchildren from St. Peter the Apostle School on Monday joined papal emissary Archbishop Vincenzo Paglia at the Center City location in choosing the flavor for a limited-edition shake.

Fifty cents from each $3.90 sale will go to planning efforts for the September meeting and for Pope Francis' visit.

The kiddies selected #PopeInPhilly, made of vanilla ice cream and shortbread butter cookies. The archbishop, president of the Vatican's Pontifical Council for the Family, eagerly supported their choice. Also in the running were World Meeting Mashup (vanilla ice cream, shortbread butter cookies and Oreo cookies) and PHL Liberty Bell (vanilla ice cream, chocolate syrup, peanut butter and bananas).

The shakes will be sold at the three Philadelphia locations (1635 Market St., Penn Tower, and 1100 W. Montgomery Ave.) from April 1 to Sept. 30.