Without these three major factors, proving that an oral contract was agreed upon can be difficult. If you make an oral contract with a stranger in business dealings then one of the two parties could easily deny ever agreeing to an oral contract or claim that such an agreement was not made in good faith.
There are two components to slime. There is a borax and water solution and a glue, water, and food coloring solution. Prepare them separately. Mix 1 teaspoon borax in 1 cup of water. Stir until the borax is dissolved. In a separate container, mix 1/2 cup (4 oz) white glue with 1/2 cup water.
Apparently the recipes for the slime varied over the years, but some of the major ingredients include Cream of Wheat, green food coloring, Johnson's baby shampoo, vegetable oil, and even sometimes cottage cheese. All sounds doable, maybe minus the cottage cheese.