Lucky hand

Two cowboys are playing cards in a saloon. One picks up a card from the table and throws it in, shouting: “I won! I won!” “What do you have?” asks the other. “Four aces.” “I’m afraid you didn’t win.” “How come? What do you have?” “Two nines and a revolver ready to fire.” “Oh, you won,” confirms the first, and asks: “How come you always have such a lucky hand?”

Why such vulgar jokes?