We see a close-up of Matt on top of Anna, kissing her (both are clothed, at a party at night), and he says he has a condom, but she says she shouldn't be there and gets up and leaves. As she does, we see another teen in a bikini top, as well as a shirtless guy, among others there.
Rachael shows varying amounts of cleavage in various outfits throughout the film, including once while sweaty after working out.
We see Alex in a bikini.
Alex sarcastically comments on Rachael once being their mother's nurse and now helping their dad cope "three times a night."
Anna hears the faint sounds of Rachael and her dad having sex (her sounds and that of the bed squeaking), and thus puts on her headphones to drown out the sound. The next day, Alex asks Anna, "Was that you or nursey in the throes of ecstasy?" They then talk about a bell their late mother used to call for them, with Alex saying Rachael got that for their mom so that Rachael hear the mom coming "while she was riding dad" (and she wiggles her body a bit, in a sexual fashion, to drive home that point).
Alex shows a little cleavage.
We see Alex in a small bikini, while Anna is in a one-piece bathing suit.
About their night on the beach in the past where he wanted to have sex with her, Matt tells Anna that he was nervous so he drank a lot, adding that he was dumb and drunk.
Alex states that Rachel is "like a crack-whore without the dignity."
While Anna travels into town with Rachael, Alex goes through the latter's stuff, looking for clues about her. When Anna returns, Alex shows some sexy lingerie she found (with a sarcastic comment about when the stripper pole is being installed), and then holds up a vibrator, saying "Meet Mr. Chubby." Anna doesn't want to hold it, and Alex removes the batteries before putting it back, stating, "Party's over, Rach."
In a sisterly and nonsexual way, Anna asks Alex to stay in bed with her until she (Anna) falls asleep, with Alex agreeing but jokingly adding, "No funny stuff."
Matt enters Anna's bedroom, wet and cold, and thus removes his shirt. The two kiss while seated on her bed, and there are some roaming hands on both parts (nothing explicit), but his spine buckles and starts to bulge out in a gross way, finally resulting in him standing but bent over badly, sideways. He grabs her and says, "Your mother tried to warn me" and she runs out of the room in fright, but when she returns moments later, it's suddenly daytime and he's gone.
Rachael puts lipstick on Anna, stating that boys supposedly like a girl's eyes, but what they really want is "a pretty mouth."
Anna and Alex each show some cleavage in their party dresses.
After sedating her, Rachael undresses Anna on her bed, down to her bra and panties, and then puts a nightshirt or nightgown on her.
We see a flashback to Anna peering through a keyhole to see her dad having sex with Rachael (both are standing, clothed, with her leaning back on a desk or something similar, with kissing, some movement and heavy breathing, but no nudity).