where do printable blue bird, black bird betting sheets from?

I'm sure some of you know what I'm talking about they are the same size probably 4×10 if I had to guess. They have terrible odds and they usually have the bet 5 on 5 win 100. They are usually passed around work places similar to how the squares are. They have just college football and nfl on them. I thought people make them but I have seen the same one all over the place even had a serial number at the bottom. Thanks