Do not answer "Yes!" so quickly, my dear Padawan, because the title question is not as stupid as it sounds.
Who has one Apple Watch obviously knows that when we receive normal calls or via FaceTime, it rings next to the iPhone. A, you can choose to answer the call over the phone or directly by the watch (using his microphone and speaker), as you prefer.
But the tip of the day is here:
When receiving a call, you can scroll the call screen on the Watch using the Digital Crown to have access to two extra options below the red and green circles: ?Send a Message? and the one that interests us here, which ?Answer on iPhone?.
The idea of ??this option is to save time until you can get your iPhone and actually answer it. It can be very useful, for example, when you are away from the device (like in a different room from your home, or maybe with it "lost" in a bag / backpack).
When selecting ?Answer on iPhone? on the Apple Watch, the person on the other end hears Siri's voice saying ?Wait a moment? and then some beeps call waiting. When you finally get your iPhone, then just slide to answer.
Cool, huh? ?
(tip from @mvcmendes, via CocaTech; images: Placeit)