An Off-the-cuff way to get a person's attention, just like a whistle, is usually a hissing sound: "pssiu!" It is not perceived as impolite, but receives seriously aggravating if recurring also typically. It is especially prevalent ahead of and during Carnival (Brazilian Mardi Gras), but also occurs throughout the year. https://wiki.moz-news.com/5-things-to-suppress-in-heed-when-choosing-the-trump-automob-3869554011751359763