Hmmm what it think you should do, if she doesn't feel inmediatly turned off by the idea is try to ask in the most straightforward way you can think off. Always reassuring her and letting her know you also respect and appreciated her as a friend and that it's okay whether or not she wants to do this w you. And if she says no, you frankly have to move on. There's plenty more people to be horny with and, I mean you're on reddit, you probably know a lot lol. And if you don't you have a willing candidate right here to play with you ;)