The fear of mexican restaurant waiters singing happy birthday to you. (or feliz cumplianos a ti or any other similar song sung in a festive manor to one person in particular) This usually happens along with the receiving of a small desert and lots of head turning. Sometimes the recipient is also required to do a dance or wear a hat.
My sister is mexa-cumplianos-serenada-phobic, and it's really funny. She starts to shake when she hears the waiters coming out of the kitchen clapping even when it isn't for her. Yeah, sometimes i feel sorry for people who have mexa-cumplianos-serenada-phobia.