Cortana is the interactive digital assistant on Microsoft's Windows smartphones. Like Siri on Apple's iPhones, you can talk to Cortana and receive verbal responses.
The engineers who designed Cortana are Trekkies, so they programmed appropriate responses into it. As you can see from the above video, you can ask Cortana to speak in Klingon.
If you don't speak Klingon, don't worry: you can also speak in English and give essential commands, such as "Beam me up" and "Set phasers to stun."
-via The Geek Twins