My son is a bit of a Jekyll and Hyde in the mornings. Some days, he wakes up full of smiles and hugs, but on others, he has what the Italians call la luna storta – the crooked moon. When he’s like this, it’s best to stay out of his way!
Avere la luna storta, often just shortened to avere la luna, is a way of saying someone’s in a bad mood in Italian.
avere la luna storta
to be in a bad mood

You might also hear svegliarsi con la luna storta – to wake up with the crooked moon – which is similar to the English expression “waking up on the wrong side of the bed.”
Stamattina mi sono svegliato con la luna storta perché non ho dormito bene.
This morning I woke up in a bad mood because I didn’t sleep well.
It is widely believed that la luna has both good and bad effects on human beings. It can make people calm and peaceful, but it can also disturb them. Just as it affects the tides, it is believed to also affect the human mind. In fact, centuries ago, many believed that the moon could drive people to madness. One man, accused of homicide, even claimed his innocence by blaming the moon!

Heather Broster is a graduate with honours in linguistics from the University of Western Ontario. She is an aspiring polyglot, proficient in English and Italian, as well as Japanese, Welsh, and French to varying degrees of fluency. Originally from Toronto, Heather has resided in various countries, notably Italy for a period of six years. Her primary focus lies in the fields of language acquisition, education, and bilingual instruction.