The SPANK packages from the missions S.A.M. Notice the resemblance between these and the hidden packages.
SPANK is a drug first introduced in Grand Theft Auto III. It is produced by the Colombian Cartel and is brought into Liberty City through several ways, including "Chunky" Lee Chong selling it at his stands in Chinatown or the Columbian Cartel itself selling it at booths disguised as espresso stands. This drug is most likely either cocaine or based off cocaine (as the hidden packages in Vice City are cocaine filled packages).
In Grand Theft Auto: Liberty City Stories, Rise FM DJ Boy Sanchez says that he tried out a new drug on the streets called SPANK which suggests that the drug was present at least since 1998. There is no clear, concise evidence that this drug was manufactured before its mentioning in 1998, but it is thought that it, or something very similar, can be seen in 1986, as a Distribution mission in Grand Theft Auto: Vice City may be used to sell a SPANK-like drug to citizens. In GTA III SPANK was sold through street stalls called the Kappa Coffee House and one of the sponsors on the Hotring Racer in GTA Vice City is the Kappa Coffee House.
Appearances
The Spanked-up madmen from the missions Kingdom Come.
The drug is first mentioned during the mission Don't Spank Ma Bitch Up, where a local thug is supplying Luigi Goterelli's prostitutes with the drug, which Luigi feels is bad for business. In the mission Kingdom Come, "SPANKed-up madmen" with bombs attached to their chests attempt to kill Claude in the Liberty Tree parking lot, a plan devised by the Uptown Yardies and Catalina.