I'm looking for a story

Hi, a while ago I read a story on a blog about two siblings, a brother and sister, both idiots, who lived with their mother on a farm. Their mother tells her daughter to castrate the cows, but somehow the sister ends up thinking she means her brother. The brother, not understanding, agrees and is castrated. Before being castrated, the brother asks his sister to make him ejaculate, and she agrees, but he takes too long, so she leaves him wanting and finishes the job.