W-allahi, ana mamnoon!
It's never vital that I use Arabic in the office, but I'll still occasionally throw around the Arabic I know. I think it can be useful to break the ice and mildly disarming for my Iraqi co-workers. Some of my colleagues are reluctant to speak English freely for fear of making mistakes. Working with an American who tries his best with their language demonstrates that perfect command of the language is not required. After I receive something I ask for, I'll sometimes respond with "mamnoon," which is colloquial gulf Arabic for "I'm grateful." More often than not, it elicits a smile in response.