it is called a box of giggles because you normally use a LOT of weed in one of them and it will burn slowly making a very strong smoke which is most likely to give you the giggles.
person 2; we could just pull it real slow or use a big bucket or something
person1; no i mean propa high how bout we unleash the box of giggles
person 2; you sure you want it??? if your gonna use your eight bag then go for it
person 1; yeh thats the stuff......time to get highhhhhhh