A Queen's Hour

In medieval times a queen was expected to travel with a large entourage and make a grand entrance that would 'wow' all guests. Therefore the queen was alloted an extra hour to prepare for all public events without being considered late. This "grace period" became known as the queens hour and was often spent discussing the queen and predicting her entrance attire. Now used in some circles to indicate when one won't be on time, but it will be worth it for the fabulous-ness of dress or personality of the late comer.

A: "The party starts in fifteen minutes"
B: "I'll be there in A Queen's Hour"