Happy crack gets its name because of its addictive properties, its sugar high, and its cocaine-like appearance. Kids frequently get suspended at school for carrying it around, and often get in the same amount of trouble as if they had brought real crack to school.
Other forms of happy crack do exist, but are not nearly as popular. These other forms generally involve mixing a powdered drink mix with sugar, though there are forms like cinicrack, which involves adding pure cinnamon to sugar, or cococrack, which utilizes raw coco powder.
Certain additives are sometimes added to happy crack, usually caffeine (though cocaine has been rumored to be used as well). This is called "super happy crack".
Please note that there are A LOT of people allergic to red 40, a food dye in Koolaid mix. If you or your friends are allergic to red 40, please do not use Happy Crack.