“Tell that horse to do his homework and buck his ideas up! Otherwise we'll go for a trip to the glue factory; and he won't be coming!”
The definition of glue is a substance with adhesive abilities. That is, something that is used between two things to stick them together.
Most shops usually sell assorted glue, as an ingredient in assorted iced biscuits. They couldn't think of anything else to put on as icing, so they decided to created assorted glues. Usually glues are NOT edible, but in sector 4.258d96 and a half of the Edible Food Act of 1932 B.C. (in all states of Australia except for Finland), there was a loophole big enough to fit the biscuits through. They couldn't fit a cake through, so there is no glue on cakes.