Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unsafe sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth (perinatal transmission). Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.

Carlos Irwin Estevez (born September 3, 1965), better known by his stage name Charlie Sheen, is an American film and television actor. He is the youngest son of actor Martin Sheen.

His character roles in films have included Chris Taylor in the 1986 Vietnam War drama Platoon, Jake Kesey in the 1986 film The Wraith, and Bud Fox in the 1987 film Wall Street. His career has also included more comedic films such as Major League, the Hot Shots! films, and Scary Movie 3 and Scary Movie 4. On television, Sheen is known for his roles on two sitcoms: as Charlie Crawford on Spin City and as Charlie Harper on Two and a Half Men. In 2010, Sheen was the highest paid actor on television, earning US$1.8 million per episode of Two and a Half Men.

Sheen's personal life has also made headlines, including reports about alcohol and drug abuse and marital problems as well as allegations of domestic violence. He was fired from his role on Two and a Half Men by CBS and Warner Bros. on March 7, 2011. Sheen subsequently announced a nationwide tour.

Jennifer Ann "Jenny" McCarthy (born November 1, 1972) is an American model, comedian, actress, author, activist, and game show host. She began her career in 1993 as a nude model for Playboy magazine and was later named their Playmate of the Year. McCarthy then parlayed her Playboy fame into a successful television and film acting career. Most recently, she has written books about parenting, and has become an activist promoting the claims that vaccines cause autism and that chelation therapy helps cure it—both claims are considered false by the medical community.

McCarthy was born in Evergreen Park, Illinois to a middle-class Catholic family of Polish and Irish descent. She lived in the West Elsdon neighborhood of Chicago. She is the second of four daughters; her sisters are named Lynette, Joanne and Amy. Her cousin is Academy Award-nominated actress Melissa McCarthy of Bridesmaids and Mike and Molly. McCarthy's mother, Linda, was a housewife and courtroom custodian, and her father, Dan McCarthy, was a steel mill foreman.