Can we do a bifurcated Limerick that at least scans in two languages at once? If it rhymes in both languages too, then so much the better, but I reckon rhyming in one language would be enough.
Un loup-garou mangeait un chat - A werewolf was eating a cat

Qu'il a pris dans un sous-sol, à bas - Which he found in a sub-basement flat
Sounds like an idea for the Wretchedly Difficult Poetry game on Orange

Quand tout à coup - When quite suddenly

Il dit "Je m'en fous" - Said "Bovvered? Not me" Don't ask me to try one in Welsh. 5 lines out of 5 is a bad form, and my Dad would turn in his grave.:-)