You meet Christina the first time you walk into the Gym. If you talk to her, she ends up expressing her concerns about her boyfriend cheating on her and offers you a 50% discounted Gym membership (and a peek at her tits) if you go check on him. After proving to her that he is, in fact, cheating on her—and with a guy—she gets angry and asks you to take a picture of her topless touching your dick. You comply and, once the picture is taken, she gets up. You can either ask her for a blowjob (which she'll give you if you punch Lucy earlier in the game), force yourself upon her (which reveals her pussy, but causes her to headbutt you and throw you out), or let her go.