Many people have their own unique birthday traditions, but in the United States friends normally give the birthday boy/girl treats or goodies. In Spain, it is the complete opposite!
In Spain, it is customary that the person who is celebrating their birthday brings in snacks or treats for all of their schoolmates or work friends, rather than the friends treating the birthday girl or boy with treats or gifts. People from the U.S. might find this tradition a bit hard to adjust to, as it is the complete opposite of the U.S. custom.
I haven't been able to find a reason that everyone in Spain agrees on for this tradition. My thought is that Spaniards celebrate their birthday by bringing in their own treat as a sign of generosity and mutual celebration.
I think this tradition is connected to the Spanish environment because it ties into the larger cultural value of generosity that I have observed in Spain. Another example that shows that Spaniards tend to be quite generous is their culture of tapas (bar snacks). You usually get a free snack with the purchase of a drink. Some bars give entire sandwiches for free.
