On a vacation in Spain, a guy goes to a bullfight. He sees the bull get killed. Afterwards he's looking for somewhere to eat and he comes across a restaurant near the bullring. He goes in and takes a seat. He can't understand anything on the menu, so he just orders the special of the day. The waiter brings out a bowl of broth in which float two large balls.
"What are these?" asks the guy. The waiter explains it's the balls of the bull that was killed in ring that day. The guy's adventurous, so he takes a bite, decides it's delicious and finishes it off.
The next day he's sightseeing but he can't resist going back to the restaurant and ordering "Bullfight Especial". The waiter brings out a bowl, but this time the balls are much smaller. He eats them anyway, finds them delicious but asks the waiter:
"Why were these balls so much smaller than they were yesterday?"