Pet Leech

I have a little leech; I bring him out to play. I really only see him Every 57th day. He’s happiest when I let him Just lie there on my arm, But I can’t let him stay too long, ‘Cuz we’ll both come to harm. And so I let him have a bit To bring my iron down, And then we get a T-shirt that We sport about the town. It would be so much better To sell him off for cash, But all they ever do with him Is throw him in the trash. Given your anemia, you could play some too; We could start a line and hook Direct from me to you.