Homemade extraction of your own DNA
Ingredients: transparent glass, salt, liquid soap, grapefruit juice, and alcohol (e.g. disinfectant, rum, vodka, etc.). The first step consists of spitting on the glass and adding a pinch of salt to it. Then, add some liquid soap (like the one you use for washing the dishes), juice from a grapefruit, and some drops of alcohol. Once you have everything on the glass, stir the mixture, et voilà. The white mucous filaments you observe on top of the mixture is your DNA.
Explanation The saliva contains cells from your mouth that have DNA inside them. The detergent is used to break down the membranes that protect the DNA, and releases it into the recipient. The salt makes the DNA denature* and precipitate, while the grapefruit juice neutralizes the proteins that could damage the DNA.