Speak English Dang It!
I know that some people can speak another language in addition to english. If you're out in public and want to converse with friends of yours that can also speak a different language, that's fine with me. However, if you're in a work place that centers around customer service, it should be a condition that around your customers you speak in the dominant language of whatever country you are in. I find it highly rude to walk into a place of business and find that two employees are conversing together in another language that the majority of the people around you don't know.