You see because CMD's joke is funny. That's the difference DUchbags. Your cow "joke" wouldn't even make a 5 year old laugh.
In fairness, my joke wouldn't make a 5 year old laugh, or a DUmmy.
The 5 year old doesn't know what a prostrate is, and the DUmmy isn't a biologist*...
*and therefore can not acknowledge that only men can get prostrate cancer, even if it does have a sense of humor, which is highly unlikely: