"To throw coals (at someone)" is to attack someone in a way which causes you at least as much damage as the person you attack.

"To lick victory from the rocks" is the equivalent of "by the skin of your teeth", but with more of a sense of hard work and sacrifice being required.

I haven't worked out how exactly to phrase it in Fubarnii, but I want an idiom "show me the money (that you have won)". This is a challenge, which says that if you claim to know something, you should be able to win money using it.

From Gill:

Having egg on your feet - criminally clumsy

Exocentric compound words are also often idiomatic. Their meaning often cannot be transparently guessed from their constituent parts. For example, the English compound white-collar is neither a kind of collar nor a white thing. In an exocentric compound, the word class is determined lexically, disregarding the class of the constituents. For example, a must-have is not a verb but a noun. The meaning of this type of compound can be glossed as "(one) whose B is A", where B is the second element of the compound and A the first. Other English examples include barefoot and Blackbeard.

www.idiomsite.com/

idioms.thefreedictionary.com/

www.idiomconnection.com/