Avoid unnecessary screams and bruises by talking with your family.
You're on the final wave of the gauntlet. Two skeleton warriors in front of you, battle casters and archers flank you left and right. 90 seconds on the clock, and your arsenal is ready to unleash a godly firestorm of righteous violence on those who dare oppose you. Left arm up to block the first wave of attacks with your shield, and the first swing from your sword lands perfectly in between the helmet and shield of the warrior in front of you. As its body crumples to dust in front of you, a smile forms on your face and you turn to take out the monster to your left. You pivot, lean a little to the left, and as your eyes meet the hollow, sunken void of the skeleton in front of you a cool hand touches your arm in the real world. Screams are heard, and a left that would have landed you in an unfortunate situation with your friends family is narrowly avoided.
Unless you live alone, people are going to unintentionally interact with you in the real world while you are enjoying a virtual world. The only thing you can do about this is have a serious conversation with your friends and family about how to approach you when your mind is clearly elsewhere.
Alright, so this is a little silly and a lot tongue in cheek, but it's something you should absolutely consider before spending a whole lot of time in VR when there are other people nearby. All of the best VR experiences available today are enhanced by immersive audio, and that means loud audio attached to a headset that fills your entire field of vision. It doesn't matter if you're sitting at your desk in front of your PC, wandering around in a room scale setup, or even sitting on the couch with your phone in a little box. When your eyes and ears are elsewhere, it's incredibly alarming for someone to reach out and touch you. In the best of situations, it's enough to cause a jump and a scare. In the worst, an accidental controller to face isn't a good thing no matter what they did.
Unless your family is also playing VR constantly with you, there's a real chance no one but you knows what is happening in VR. This is fairly easy to fix, though. Here's some quick tips.
Make sure everyone knows that you can't hear or see them when the headset is on. Even if you've responded when called to in the past, it's best to assume the user can't hear anything in the real world.
Show your friends and family your PC monitor, where they can see what you can see in the virtual environment. If they can see you're in the middle of something, they are less likely to interrupt.
Encourage a specific kind of interruption when necessary, like removing the headphones and speaking immediately. The random touch on the body is jarring, but moving the headphones immediately reminds the user that the real world is happening.
Remember to check your physical environment occasionally. On the HTC Vive, this is as easy as a double tap on the home button to engage the camera on the front. Elsewhere, you'll need to lift the headset up every once in a while.
Ultimately this is a complicated way to avoid accidents in VR, be they something physical like accidentally hitting someone or emotional like realizing the icy hand of death as the cockpit of your spaceship explodes is actually your wife letting you know dinner is ready. As long as everyone is on the same page, fewer incidents will happen. Unless, of course, you have friends and family that want to mess with you on purpose. That's a topic for another day.