HELLO! I'M AT A WEDDING!
From the ever so helpful Cambridgeshire Registrar's Office site:
Please remind all concerned (especially the groom!) that mobile phones should be turned off before entering the building where a marriage is to take place, otherwise you could have the "Flight of the Bumble Bee" or "Old MacDonald" going off part way through!
If anyone plays "Old MacDonald" at me on our wedding day, they will quickly discover the discomfort of a little plastic bride and groom lodged in a random orifice.