Designer drug
Other names for designer drugs are "bath salts" or "plant food."  The real chemicals in these drugs are mephedrone, methylone, and methylenedioxypyrovalerone (MDPV).  By writing "Not for human consumption (eating/drinking)" on the bags sellers are able to find a way around selling them online and in stores.  Using labels like this help companies get around the Federal Analog Act which makes it illegal to sell drugs like these for human use.