Most Helpful Guy
You are definitely not being ridiculous. The complex and corrupt social culture that got you nervous about this is ridiculous, but not you, if that makes sense.
In order to overcome your anxiety, I think you should know where it comes from. Think about it and ask yourself why you're nervous. If I have to speculate, I'd say you're nervous because you're worried he might not like something or another--the scent, the taste, etc. If that is the case, you should remember that you wouldn't let him go down on you just for him, but for you. You should be enjoying oral sex for him to enjoy it. Why? Because most people who enjoy giving oral sex do because they like to please others. I think that remembering that would help you let go.
Also, if you trust the guy to be mature and rational, talk to him about it. Tell him you're nervous and see what he can do to help you overcome that.
We can discuss this further if you want, but I don't want to be too long.
Hope this helps :)