"Cleaner than a frog's armpit"

That's a Spanish idiom listed in a discussion of that curious linguistic device in a column in today's Guardian. The phrase has nothing to do with cleanliness; if refers to being broke.

The definition of an idiom is a phrase whose meaning isn't clear from the words in it... They are cryptic language puzzles, solvable only if you already know the answer in advance.

Here's a quiz of your knowledge of worldwide idioms, using other examples offered in the article (answers at the link):

To seize the moon by the teeth. (French).
To reheat cabbage. (Italian).
When the crayfish sings in the mountain. (Russian).
To think one is the last suck of the mango. (South American Spanish).
Onions should grow in your navel. (Yiddish).
Brew tea from dirt under another's fingernails. (Japanese).
Belch smoke from the seven orifices of the head. (Chinese).

Idioms were also addressed in an article at the Onion.