probably best to buy a new girlfriend every night you want one !!! that way you don't get bored with the same old girlfriend or have to listen to her whinge and bitch, or want you to do stupid stuff like shopping etc etc............Of course important stuff like going out with your mates and having a good time takes precedence and generally 2 or 3 three girlfriends a week is sufficient so it actually quite cost effective providing you don't do anything stupid like fall in love with/marry one!!!