[spoiler]Let me explain it to you like you're 12 years old.[/spoiler] It is a male face, but everything else in the pic is female. The only thing he's implying is that Caitlyn's face is not particularly appealing like that of the man depicted. The humor is in the resemblance of the situation in the portrait -- a manly face on a woman's body -- to the reality of Caitlyn's situation.