A man comes home from work and sees his wife on the bed with another man. He takes his gun and says to the other man:

If you want my wife come take her from me like a man. I challenge you to a duel

The other man accepts his challenge, they go to the other room and close the door. The husband tells the other man;

Actually, nobody has to get hurt. Lets shoot into the air and pretend like we are both dead. And we will see what my wife will go to who firstly, so she loves him more.

Then they shoot in the air and lay on the ground. The woman runs into the room and sees both men on the ground and shouts:

Honey, you can come out, they both are dead!