Dangerous Sharp Eraser

I have two brothers and they like making fun of me.
One day, my older brother tried to make an eraser sharp.
If this was the eraser, he tried to use one edge and the opposite edge to sharpen it.
A few weeks later, it became as sharp as a knife. He jokingly struck at my little brother with the sharp eraser, and mimicked its sound "Saku". He said that if a knife was really sharp and you struck into one's body, it would sound like that. Next, he also struck at me with it, and said "Busu". In Japanese, "Busu" means an ugly woman. They were laughing at me loudly. I got a little angry.
My brothers always enjoy teasing me; however, I’m getting along with them.