1. To take a poop with the implication that your turds will be so huge that you will have lost ten pounds by the time you are done pooping.
2. To weigh yourself before and after a poop to see how much weight you lost.
1. Danny was so full from the meal that he announced to the table, "I'm gonna go lose ten pounds" as he excused himself to the bathroom.
2. "You hold down the fort, I'm gonna go lose ten pounds", announced Bill to his hunting companion.