So, an idiom is an expression that doesn’t mean exactly what it says. Examples? Pull up your socks. Stick your neck out.
A friend currently travelling the world, leaving me totally jealous in cold, cold Melbourne, found a book of French/English translations of idioms with some amusing drawings. Just check these out.

I can only hope I remember to tell people not to pass from cock to donkey in the future.

I don’t understand this one at all… It’s not brilliant. It doesn’t break three legs to a duck. Nope. Don’t get it. Break three legs. Duck. Hmm. Any thoughts?

I think this translation is actually that the situation is turning to piss. A bit like shit hitting the fan? Oh, very glad there’s no cartoon for that one.
Inspired by these cartoons (thanks, Cynth!) I’ve gone looking for other translated idioms. From www.omniglot.com
Arabic: I don’t have a camel in the caravan (meaning : this matter doesn’t concern me)
Armenian: Stop ironing my head! (meaning : stop annoying me!)
Cheyenne: Are you still riding the goat? (meaning : separated from your spouse) Perhaps a bit like being in the doghouse?
My tapeworm can almost talk by itself (meaning : My stomach is growling)
Estonian: To make something out of wood and paint it red (meaning : to make something really clear)
French: I have other cats to whip (meaning : I have other fish to fry, or I have other things to do)
Hindi – Loosing of all body parts (meaning : to get very tired)
to excrete embers (meaning : to get very angry)
Indonesian – the bacterium across the sea is seen but the elephant on eyelid is not seen (meaning : missing the obvious)
Italian – to have one’s eyes lined with ham (meaning : can’t see the wood for the trees)
Japanese – even monkeys fall from trees (meaning : even experts get it wrong)
Russian – to hang noodles on one’s ears (meaning : to tell lies)
Serbian – he’s ripping clouds with his nose (meaning : he’s conceited, puffed up)
Tibetan – to put up a beer tent (meaning : to get married)
I was going to check out other sites, but I just don’t think I can beat these. So, again, thanks to Cynth and to omniglot!