A plastic grocery (liquor store/beer store) bag filled with every flavor of Four Loko which come in many assorted color cans therefore making the bag look like a rainbow. Four Loko is constantly releasing new flavors so it is hard to keep up with them all which is why a rainbow bag only needs to have at least all 5 of the "original" flavors : Fruit Punch, Orange, Uva (Grape), Watermelon, and Blue Raspberry. Watermelon and Blue Raspberry were not "original" flavors but are the 2 oldest flavors that weren't launched with the company.
John: What did you get man?
Tim: Got us a fucking rainbow bag!
John: Oh fuck, good looks son, were gettin' wasted tonight.
To pass a beer between a group of people (could also be 2 people), Primarily a 40 ounce or a Sidewalk Slam (see Sidewalk Slam) but it could really be any beverage including non-alcoholic. The people enjoying this beverage usually sit in a circle, take a swill and pass the beer to the next person in the circle therefore making the beer "spin" in a circle. Taking more then one swill is considered bad etiquette and depending on who you are with doing so could get you in some trouble. This term is Primarily used by punks, squatters, travelers and I guess unfortunately dirty hippies.
Bill: all I got is 75 cents
John: same here...
Tim: well I got a buck
Bill: lets get a 40 and spin that shit!
John and Tim: fuck yeah!
Bill: hey man what did you do yesterday?
John: not much man, just sat at Tims house and spun some beers
John: yo Tim where you at?
Tim: Sittin in the woods with mad heads spinnin' some beers man.