A man and his wife are visiting Mexico and go to the local restaurant for dinner. They can't seen to decide on what to have so they spend a lot of time looking over the menu. While they are looking, they hear a trumpet fanfare, and out of the kitchen comes the cook with a big platter. He is accompanied by two or three waiters and with much ceremony, they place the platter on the next table and uncover it to reveal two rather large grounded pieces of meat surrounded by vegetables and lots of garnish.
The man and wife ask their waiter what that was all about and the waiter explains that the next table was just served the house specialty—the testicles of the bull from the day's bullfight. The man and his wife ask for the same dish and the waiter explains that there is only one bullfight per day so they can't have that dish tonight, however, they could be the persons of honor tomorrow night and that makes the couple happy.
They return the next day and await the feast. There is the trumpet fanfare, and the big procession and all the hoop-de-do and they set the platter down and uncover it only to reveal two rather small morsels. When the man asks the waiter, " what gives—yesterday's were so much larger?"
To which the waiter replies, "Well senor, you must understand, some days the bull wins."