I want to show my friend nude pics a girl posted on her Snapchat story
Why do you want to show your friend nude Snapchat pics of some girl ?
It is a fun idea
Do not assume that your friend wants to see someone's naked pictures. Your friend may be offended by this behavior and you should respect that.
My friend is okay with it and I'm going to show him those pics. I think it's going to be hilarious.
You cannot be sure about it. Even he wants to see those nude pics, it's wrong to be too nosy in someone's private affairs. Find something else to entertain yourself.