Lisa is one third of Tiffany and Brittany Wilson's trio of good friends. We are first introduced to her when FBI agents Kevin Copeland and Marcus Copeland, who are posing as the rich Wilson sisters, bump into her at The Hamptons. She is with the other two women in the trio, Karen and Tori.
Despite how familiar she is with the [fake] Wilson sisters, it is mentioned that none of the trio have seen the sisters for over a year, suggesting either a significant difference in location or a more shallow friendship.
Lisa may be seen as not particularly bright. Neither her nor her two friends realise that the sisters are being impersonated, despite the difference in height (which Lisa actually does notice), personality, body build, face shape, voice, and other details.
She and her friends may also be interpreted as rather immature for their age. In the same way that school girls are often portrayed, the trio are very excitable about subjectively shallow activities such as shopping. They also insist on going to the restroom together, and hold a regular slumber party, much as young girls might.
In spite of this, the young women appear to have a strong bond. They do not quarrel even when they disagree with each other, and although they seem disgusted by [fake] Tiffany Wilson's bathroom problems, they kindly ask if she is all right, and then wait outside and do not mention the embarrassing incident again.
Although it is implied that Lisa and her friends are sexually active, they ask the [fake] Wilson sisters for tips on how to best perform oral sex on a male - perhaps suggesting they haven't had much experience or that they are not confident in their sexual abilities. Here they again display an immature side by becoming very giggly about having a sex toy to demonstrate on.
When the friends go shopping, it is revealed that Lisa has a very poor view of her own body. She and [fake] Brittany Wilson separate from the others to look for clothes (for Lisa). However, the trip isn't very successful, as she becomes extremely distraught whenever she sees herself in different outfits. Whilst the male FBI agent describes her as sexy, Lisa asks if "Brittany" is joking, and goes on to point out her [non-existent] cellulite and supposedly fat stomach.
Despite this, there are moments when Lisa shows a more confident and sexual side, such as when she dances seductively with Karen to help Karen arouse the man she is seeing.
Throughout most of the film, Lisa could be described as more of a follower than a leader. She does not take charge or lead the group in any particular action. For example, it is Tori who takes Lisa and the others shopping and to the Magazine Reception and, later, it is Karen who is responsible for humiliating the Vandergeld sisters (who are said to be the Wilson sisters' "sworn enemies").
The film ends with Lisa, Karen, and Tori admitting that they liked the "Wilson sisters" better when the FBI agents were pretending to be them, and with the agents assuring the trio that they will still see each other.