If you can get a girl over and fuck her before a night out with your boys then the night is already a success and you don't have to worry about bringing a girl home and getting laid. Your resultant carefree attitude is then more likely to net you ass you probably wouldn't have obtained if you were actively seeking it out. The outcome, therefore, is a double positive.*
*Most people will cite the loaded gun, There's Something About Mary scene to counter this hypothesis, but anyone who's ever had sex knows that a nut in the hand is worth negative two in the bush.