"toilet papering", is often favored by adolescents and is the act of throwing rolls of toilet paper over cars, trees, houses and gardens, causing the toilet paper to unfurl and cover the property, creating an inconvenient mess. Children and cats may unroll an entire roll of toilet paper by spinning it until it completely unravels on the floor, or as a game by children wadding up one end, putting it in the toilet bowl without tearing it and then using the flushing of the toilet to pull new paper into the toilet, with the objective of flushing the entire roll down the toilet section at a time without the toilet paper breaking. Special toilet paper insert holders with an oblong shape were invented to prevent continuous unrolling without tearing to discourage this practice. Toilet paper pranks include musical toilet paper holders and inserts that are activated by the unrolling of the toilet paper and will loudly play an embarrassing song calling attention to the person defecating. Other gags include custom toilet paper printed with jokes, stories or politician's images. Mechanics Alexander Balankin and coauthors have studied the behavior of toilet paper under tensile stress and during wetting and burning. Toilet paper has been used in physics education to demonstrate the concepts of torque, moment of inertia, and angular momentum; and the conservation of momentum and energy. Environmental considerations One tree produces about 800 rolls () of toilet paper and about 83 million rolls are produced per day. Global toilet paper production consumes 27,000 trees daily. More than seven billion rolls of toilet paper are sold yearly in the United States alone. Americans use an average of 141 rolls per capita a year which is equivalent to of tissue paper per year. This figure is about 50% more than the average of other Western countries or Japan. The higher use in the United States may be explained by the fact that other countries people use bidets or spray hoses to clean themselves. Millions of trees are harvested in North and South America leaving ecological footprint concerns. , between 22% and 48% of the toilet paper used in the United States comes from tree farms in the U.S. and South America, with the rest mostly coming from old, second growth forests, and, some from virgin forests. Alternatives to virgin wood pulp Toilet paper made from recycled paper avoids the direct environmental impact