If you’re a friend, then hopefully you know the person well enough to have an idea of what types of things they’d be comfortable discussing with you, and will respect their boundaries. Some friends are comfortable talking about their genitals with each other and some aren’t, for example. And hopefully you will respect your friend enough to try to avoid insulting them. These questions are things that are either totally inappropriate to ask out of the blue (like the penis question) or are phrased in hurtful ways (like asking someone what their “real” name is). Hopefully, with a friend, you would have an idea of whether they’d be comfortable discussing their body with you. And you’ll know that the name they go by is their real name.