A feeling that arises from a bitter-sweet moment in which you are happy (or "Stoked") about a particular circumstance, while simultaneously saddened (total "Bummer" dude!) due to a consequence of the same event. Only really applies to people in Souther California, or events taking place there.
Me: Dude, so I'm stoked that my little sister is getting a sweet gig in Portland but I'm bummed-out that it means she will be moving out of SoCal.
Buddy: Yeah, Stoked Bummer man.
Me: Double True.