WordWeb Online

1. (of an automobile) having the engine modified to give extra power
   "a hopped-up jalopy"
    
2. Under the influence of narcotics, especially cannabis
   "We were hopped-up most of the time";
   - stoned [informal]

See also: drunk, gone, inebriate, inebriated, intoxicated, powered, ripped [informal], skunked [informal]