This afternoon, while on my way to the school, I passed by to three kids playing with yoyo. One of them was holding a yoyo marked as protostar yoyo. It was colored black and a bit bigger to the other yoyo which other kids were holding.
Just in time when I got nearer to them, the boy who was holding the biggest yoyo among the three badly hit the boy in front of him in the forehead.
Swollen forehead (image source and credits)
After not less than five minutes, the forehead of the boy who was badly hit by the yoyo swell and inflamed. I even witnessed how the boy really felt in pain because I halted from the moment he was hit.
The image above is not the boy who was hit by the yoyo but I am just showing that his forehead is something like that above, swollen.