SOmeone told me that this is how Jewish people have to have sex.
They cut a hole in a sheet and drape it over the woman, then they have sex through the hole. and that they're real strict and only have sex for procreation, not for fun.
I'd say that practice is really rare these days. I've read somewhere about that being done by very Orthodox Jews, but I think that, even among that group, it is not done very often anymore.
Some religions do believe that couples should not have sex unless they desire to have a child as a result, but that does not necessarily mean that they do not derive pleasure from sex when they do have it. Everyone has a different take on it, and enjoys sex in different ways.
Just wondering, but where did you hear about this?