Let’s look at the use of the word “ball” in idioms (modismos). It has some interesting uses and here are some examples.
- Mr. Rajoy is “on the ball”. This means that he is on “top of his job”. Perhaps in Spanish you might say “es muy espabilado” or «está al tanto”.
- Mr. Corbyn, the Labour leader, is “no ball of fire”. By this we mean that he is not dynamic (dinámico).
- Ricardo always “has several balls in the air”. Here we mean that he has to manage or juggle (in this context, in Spanish “compaginar”) many things at the same time.
Finally, if you wish to say that something is nonsense, you could colloquially (coloquialmente) say “it is balls”.