I want to but should I?

So one of my friends has offered to go down on me a ton of times and I really want him to but we're not together in any way just friends and he dated a friend of mine for like a week a while ago, plus I feel like my friends will think bad of me if I do. I really just want to be satisfied but I don't want my friends to think bad of me. What should I do? Should I ask my friend if it's fine with her, cause she is currently dating someone else.