I'm not sure there is a universal rule on this but when a sister gets lavaliered, it is traditional to hold a candle pass to reveal her good news to the chapter and to celebrate the event.
At my university, the corresponding male's fraternity used to give him a chiding for "giving his letters away." It usually came in the form of pouring a liquid beverage or some food on him at an unsuspecting moment. However, I think that might have just been my university.
lol
