Female condom.

I was reading an it said you should use a condom for oral if you know the guy is having sec with other ppl. This guy hasn't had sex with anyone for at least 2 months and I'd like him to perform oral on me... I know if I were to do it on him I should use a condom. But if he were to do it on me, do I need one? A female condom? Do those exist? Where do I get them? How do I use them?