The First Order takes all kinds of babies, but mostly humans. Finn always assumed he was human, like the majority of the other Troopers, since he looks pretty human. But then why does his partner look so startled when they see him naked for the first time?

In which Finn & his partner discover he's actually a (mostly human-looking) alien with alien genitals.

+ Finn is equally weirded out by his partners genitals, having expected them to be more similar to his own
+ his partner is super enthusiastic to try something new and figure out how to make it work