Assuming both parties understand that this is just-friends and nothing more, just for the pure enjoyment of sex, would you sleep with a friend? Neither party is lusting and/or in love with the other, this isn't leading to a greater relationship, this is just sex.
I find it kind of weird that you would sleep with a friend. I can understand why it wouldn't be considered weird and why it wouldn't be a bad thing, I just don't like the idea of it. It seems unnatural to me, has never sat right with me. Sex to me is just something that two people do to show each other how much they love and enjoy each other.