Haley: Nathan, I know I’m driving you crazy.
Nathan: No, you’re not.
Haley: Do you think that I’m a tease?
Nathan: Stop it.
Haley: Well, what do you think?
Nathan: I think that you’re my girlfriend, and I like to spend time with you. Look, I just don’t want to push you.
Haley: You’re not.
Nathan: But I am. Haley, you got a tattoo for god sakes. It just freaks me out a little bit because obviously this whole thing with us means a lot to you. I just don’t want to do anything to pressure you. Or drive you away. Even though sometimes I can’t help it. Just like I can’t help that I fell in love with you. 'Cause I did. I love you, Haley. And it scares me a little bit but there it is.
Haley: Wow. There it is. I love you too.

Lucas: What do you mean, you think?
Brooke: I mean I’m late. Like, late.
Lucas: Did you take a test? Okay. Okay, um, look, we have to know, okay? Maybe it’s a false alarm, you know? Come on. Drug store’s still open. We’ll do it together, okay?

Nicki: All the babysitting in the world won't make you her mother.
Peyton: All the eyeliner in the world won't make you more than a psycho-stalker bitch.

Brooke: I lied.
Lucas: What?
Brooke: I'm not pregnant.
Lucas: But I saw the test.
Brooke: I know. And when the doctor called, he said I wasn't pregnant. He said that can happen.
Lucas: Okay, no-no-no-no. I -- I was standing right there when he called.
Brooke: And you had just called me a slut.
Lucas: So you lied to me to punish me?! How could you do that?
Brooke: How could you cheat on me with my best friend?
Lucas: Brooke, I never meant to hurt you.
Brooke: That doesn't really matter, Lucas. 'Cause in the end it all hurts just the same.

In the photos of young Lucas, the team name on his jersey reads Clarence, not Tree Hill. Lucas grew up in Tree Hill and his jersey should read Tree Hill instead.

When Brooke tells Lucas that she lied about the pregnancy, a camera man can be seen in the mirror next to Brooke's bed.

Episode Title: How Can You Be Sure?

"How Can You Be Sure?" is the title of a song by Radiohead.

The episode title, "How Can You Be Sure?", is a reference to both Haley deciding whether or not she should have sex with Nathan, as well as Brooke forming a friendship with Nicki.