To all the girls (and maybe guys) who in this thread or irl said "eww thats gross" or "why dont you stick a cock up your ass, see how you like it". I bet you said the same type of things when you were little, about regular sex. "eww thats gross" or "im not doing it you do it". Maybe its time for you to grow up some more. No, in fact its definitely time for you to grow up.
The question from the OP is not "my girlfriend definitely doesnt want me to stick my dick up her ass, but i want to do it anyway, fuck that bitch" its "shes shy about it, i need help in to show her it coulod be enjoyable". If he had asked it the first way, then that would warrant these ridiculous responses. Grow up.
I'm sure he knows it would hurt to get fucked in the ass. But there are millions of girls AND guys that do it everyday. Its not taboo anymore. You know in the old days having sex before marriage was just as taboo as anal sex used to be. Now you can hardly find anyone nowadays who waits till they're married. Its 2008. Get with the program.