We've all been hit in the eye by a Nerf dart at one point in our lives.
It can be pretty painful, but just be thankful you weren't hit by a dart from Mark Rober's Nerf gun - because his shoots darts at 40mph. And he says it's the biggest in the world.
The former Nasa engineer's YouTube channel is full of great inventions, creative hacks, and popular science - like this one detailing how to make a snowball gun.
And if while watching the video you couldn't stop wondering who would win between that gun and a watermelon, look no further.