The reason why you can't name your kid Friday in Italy is because of Italie's, strict naming laws (Article 34 of Law 396/2000) forbid names that are "ridiculous, shameful, or likely to limit social interaction."
Friday translates to Venerdi in Italian.
Italian courts have also famously banned a couple from naming their kid Friday in 2008, and cited 3 specific reasons for banning of the name Friday for their kid.
The 3 specific reasons that the court stated for banning the kid Friday includes.
Association with Misfortune.
The judges in Italy noted that a day of the week can carry associations with penitence or even bad luck.
Fear of Mockery.
The Italian court also determined that the name "Friday" was also susceptible to irony and mockery and would turn a boy into a laughing stock if they were named Friday.
And literary Stigma.
Judges in Italy also ruled that the name Friday recalls a subservient native character in Daniel Defoe's novel Robinson Crusoe.
They also felt that the name Friday was associated with subservience and inferiority.
So because of these protection in Italy, registrars of names re legally empowered to reject baby names that could cause a child any embarrassment or limit their social development.
You could call your child or kid Friday in Italy, but you can't legally name your child or kid or baby Friday in Italy.