Abusive language is never okay. No matter what country, no matter what city. You should always show respect to strangers and use subtle, kind language. Swear words and aggressive tones should be kept for private- you can seriously disrespect parents with their small children, the elderly and even other tourists if you go barking foul language around the streets. Not to mention crude words are forbidden in many countries, so unless you want to see a jail cell- Keep it clean.