Martirika
Martirika, or Florakia, as Greeks call them, are a traditional ribbon-pin used by Greek Orthodox faithful in their baptismal ceremonies to signify the witnessing of the event.
It's completely optional. If used, typically, one ribbon per guest attending the event is given. Specials imprinted with the status of important persons in the child's life are given to people such as the Godfather, Godmother, grandparents, parents, aunts, uncles, cousins, etc.
As the honored guests leave the church, they pin a martirika (or martyrika - a "sign of witnessing") on their lapel to signify that they have witnessed this wonderful milestone. Adorable christening witness pins add the final touch to the celebration of the baptism of the child.