El Español's "Dictionary of things in the English Language by a fellow Student"

below the belt (exp.) 

- A sneaky tactic employed by matadors who are losing a bullfight. Involves hitting the bull in an unsporting way, much like criticizing someone's paella recipe when they're not around to defend it.

In bullfighting: When a matador, out of desperation and failing to impress the crowd, resorts to tripping the bull with his cape or tickling its underbelly with a feather.

In a tapas bar: Whispering to your friend that their tortilla española is drier than the Sahara Desert, then quickly changing the subject when they return from the restroom.

In flamenco dancing: Secretly untying your rival's shoe laces just before they take the stage for a passionate performance.

In a siesta competition: Hiding your opponent's alarm clock so they oversleep and miss the afternoon nap session.

In a paella cook-off: Sabotaging your competitor's dish by replacing their saffron with yellow food coloring and their chorizo with hot dogs.