I had a boyfriend with a curved penis. it cuved toward his stomach and I must say...did not hurt for him to do any position. at least as far as I know...we were very sexual. it did hurt me to do doggie style. I am not sure what your sister's boyfriend can do, but it is unfortunate that it hurts. can it be that he is shy and only likes certain positions? but maybe a doctor should look at him. my boyfriend had a pretty large 'bend'. it was for no reason that I know of, other then that is the way he was born. He has a large penis and it was good in many ways I hope those two can figure out what to do. or maybe they will just be stuck in missionary forever. but that doesnt have to be a bad thing *shrugs as far as the man *alex?* with the curved penis and what his GF will think.... of she loves you, she wont think anything. hopefully, you both are comfortable enough to discuss it. like all vaginas are different, so are penis'. I think she might like it. I loved my ex bf's curved penis. the truth is he was my first and i thought it was pretty normal:P didnt have much to compare it to. actually thought ALL men's penis' were like that and I loved his penis. I found out later that they are supposed to be straight....supposibly. no worries:) unless it twists like a corkscrew, I am sure she will see it as any other penis. and if she doesn't, talk about it. if she doesnt find it acceptable, (which I do not think will happen)...it would be her loss