lol NB finally asks a serious question. I think you need to be a little big more strategic when trying to get in that ass. It has always been my philosophy in regards to anal sex that you must first grease the wheels up a bit by eluding to anal sex in some funny jokes while you are on the phone. Like if you call her up tonight and ask how her day was and she tells you, "oh it was ok, I had lunch with a few of my old friends from high school and just had the best time." Then you immediately you pop in and say "HAHA...LIKE ANAL SEX, RIGHT?!" Even if she doesn't start laughing hysterically, you'll have at least planted the seed, and she'll be thinking about taking rod in the pooper for the remainder of the evening, possibly the whole week. But just to be sure, make at least a couple more similar cracks(hehe) at some point before you see her again.
Then once Friday night comes, go out and get ripped. It doesn't really matter if she's drunk or not, just as long as you are. Sneak a flask in your sock if you have to. Then when you get back home, and you two are fooling around on the bed or whatever, it's pretty much smooth sailing. She'll probably already be planning on having sex with you that night, so once the drawers have been dropped, put on the rubber and turn her over her stomach. Fumble around trying to put it in like you're not really sure where the vagina is, but in the back of the mind you know damn well you are trying to push it in the butt. She may struggle at this point trying to put it in the bush for you, but keep at it(pushing her hands away, slapping her on the back of the head) until either the cops show up, or she hits you in the head with a lamp and knocks you out.