dope
1.  Term used for drugs of abuse, e.g. stimulants (cocaine, methamphetamine, Ritalin--"Kiddie Speed", etc.), opiates (heroin, OxyContin, etc.), dissociatives (PCP, ketamine--"Special K", DXM--"Robo"), cannibis, benzodiazepines (Valium, Xanax, etc).  Probably originates from the dopey shit people do when they use large amounts of the above substances.

2.  Cool, phat, bad, hip, hot, in, etc.  Probably originates from the association of dope (drugs) with being cool and having a good time.
1.  I'm seriously fiending for some good dope right now.

2.  Damn, that girl looks dope!