In Britain, wizards celebrated muggle holidays - or muggles celebrated wizarding ones, depending on who you asked. The cultures hadn't diverged enough to make them unique.
In Italy, Sirius discovered, it was another matter entirely. The muggle streets had been the same as always, but when he'd ducked down an alleyway to avoid some unwanted attention, he found himself firmly in wizarding territory, surrounded by grinning masks and the wonderful chaos of a street festival.
He charmed a mask off a pretty vendor with his trademark smile. Hah. Guess James had been right when he'd said not even Azkaban -
Don't think about that now, eh?
Snuffles would have been safer, but Sirius didn't want to scrounge for scraps today. Didn't want a kick to send him to the gutter his mother had predicted. He would be human today, masked but free.
He started an old juggling trick that had once impressed girls. It earned him enough for sweet sticky ice that Remus would have loved and for two bright birds to send word home.
He slept on top of a stall's canopy, listening to musicians play and smiling at his star.
He dreamed of Quidditch with James and woke up smiling.