Xannies is a slang term for Xanax, an anti-anxiety medication often abused by satan worshiping skateboarders.
> "I slipped myself some pink Xannies
> And danced around the house in all-over print panties
> My mom's gone, that fucking broad will never understand me
> I'm not gay, I just wanna boogie to some Marvin"
> -Tyler the Creator (yonkers)