The first girlfriend decides to get a total makeover with the money. She gets new clothes, a new hairdo, manicure, pedicure, the works, and then tells the man, "I spent the money so I could look pretty for you because I love you so much."
The second girlfriend decides to get new golf clubs, a CD player, a television, and a stereo, and then gives them to the man. She says, "I bought these gifts for you with the money because I love you so much."
The third girlfriend decides to take the $5000 and invests it in the stock market, doubles her investment, then returns the $5000 to the man and reinvests the rest. She says, "I am investing the rest of the money for our future because I love you so much."
The man thinks long and hard about how each of the women spent the money, then finally decides to marry the one with the biggest boobs.