smarties noun tablets of MDMA, the recreational drug best known as ecstasy UK From a branded multi-coloured confection.
One of it [MDMA]’s early nicknames, “disco biscuits”, was a reflection of how sweet and safe the drug was considered, like “Smarties” (another nickname). — Dave Haslam, AdventuresoftheWheelsof Steel, p. xxv, 2001