So I showed him this picture and...
...he said, "No! Your sister looks like you!" To which I replied, "Are you saying I look like a pregnant woman?" to which he replied, "No. Well yes. But in a good way. You have the same freckled chest."
"Are you sure that's what you mean?" I asked.
Fumbling ensued.
Result: I actually look like a pregnant woman.
Moral of the story: never ask a coworker if he wants to have sex with your pregnant sister.