The movie The Addams Family (1991) featured a scene where a Girl Scout asked Wednesday Addams if her lemonade was made from real lemons:
 
Girl Scout: I only like all-natural foods and beverages, organically grown, with no preservatives. Are you sure they’re real lemons?
Pugsley: Yes.
Girl Scout: Well, I’ll tell you what. I’ll buy a cup if you buy a box of my delicious Girl Scout cookies. Do we have a deal?
Wednesday: Are they made from real Girl Scouts?
 
The 1991 movie line has remained popular. A similar joke is “If peanut butter cookies are made from peanut butter, what are Girl Scout cookies made out of?”
 
   
Wikipedia: Girl Scout Cookies
Girl Scout Cookies are cookies sold by Girl Scouts of the USA (GSUSA) as one of its major fundraisers for local Scout units. Members of the GSUSA have been selling cookies since 1917 to raise funds. Girls who participate can earn prizes for their efforts. There are also unit incentives if the unit as a whole does well. As of 2007, sales were estimated at about 200 million boxes per year.
   
Wikipedia: The Addams Family (film)
The Addams Family is a 1991 American comedy film based on the characters from the cartoon of the same name created by cartoonist Charles Addams.
 
The movie was originally developed at Orion Pictures (which at the time owned the rights to the television series on which the film was based due to its ownership of the Filmways library). But due to the studio’s financial problems, Paramount Pictures stepped in to complete the film and handled North American distribution, with Orion retaining the international rights (these rights now belong to Metro-Goldwyn-Mayer through their purchase of Orion). The film debuted in Los Angeles on November 16, 1991. It opened internationally on November 22, 1991, on the same day as An American Tail: Fievel Goes West and Beauty and the Beast and received positive reviews. It was followed by a sequel, Addams Family Values, in 1993.
   
The Internet Movie Database
The Addams Family (1991)
Quotes
Girl Scout: Is this made from real lemons?
Wednesday: Yes.
Girl Scout: I only like all-natural foods and beverages, organically grown, with no preservatives. Are you sure they’re real lemons?
Pugsley: Yes.
Girl Scout: Well, I’ll tell you what. I’ll buy a cup if you buy a box of my delicious Girl Scout cookies. Do we have a deal?
Wednesday: Are they made from real Girl Scouts?
 
Google Books
Net-Wit.Com:
A Smorgasbord of E-Mail and Internet Wit Blended with Humorous Incidents from the Author’s Wild and Wooly Life
By Marv Rubinstein
Rockville, MD: Schreiber Pub.
2000
Pg. 73:
If peanut butter cookies are made from peanut butter, what are Girl Scout cookies made of?
 
Twitter
Lily Fox
‏@lilylayer4
“Are they made from real Girl Scouts?” - The single favourite line of my childhood.
1:49 PM - 14 Nov 13