Little Lacy Surprise is a "fashion underwear" brand for children first mentioned in Grand Theft Auto: Vice City Stories, later introduced as a website in Grand Theft Auto IV, and also referred to in Grand Theft Auto: Chinatown Wars and Grand Theft Auto V.
Grand Theft Auto: Vice City Stories
Allegedly, the underwear comes in a range of "styles" with the cartoon characters The Barfs and also comes in unisex. It also features other cartoon characters, according to the ad from Radio Espantoso, although they have very suggestive names, being "Horny the Unicorn" ("horny" is a well-known word for sexual arousal) and "Tapeworm" (in reality, tapeworms are parastic infections).
Grand Theft Auto IV
In GTA IV, the company supposedly hosts a website about a pageant sponsored by them. Upon accessing the closed website, the player receives a 5-star wanted level since the LCPD are controlling it because of its pedophilic content.
Grand Theft Auto: Chinatown Wars
One year later, in 2009, Huang Lee receives an email from "Illegal Teen", which indicates a site in which child pornography is available to see, and furthermore says it is surely legal and that they "wouldn't lie to people where money was concerned", finishing the email by saying "the FIB no longer controls the site*", with a post scriptum "*on an hourly rate".
This FIB reference and the pedophilia involved clearly points out that the site is indeed littlelacysurprisepageant.com.
Grand Theft Auto V
The Little Lacy Surprise brand is mentioned during the mission Deep Inside by the actress kidnapped by Franklin, she says that when she was three years old, her parents put her in a Little Lacy Surprise commercial.