The Bones Brigade were a successful and popular skateboarding team which released videos in the mid-eighties. Possibly best known for having Tony Hawk as a member. This sets the time period of her late teenage years where part of the album takes place.
On a superficial level, she’s literally going to leave him for whichever drug dealer can get her the highest. See Girls Like Status.
Holly is getting ready to take the leap to faith, but this can only happen after she has found an object of belief which is sufficient. Or, as she puts it, as soon as she finds “whoever’s gonna get me the highest” (i.e. closer to heaven or a divine ideal, as well as who will provide her with drugs). This shows the parallel between drugs and Christianity that the band uses often.