Adhesion, a difficult word from the chemical world, something with molecules attaching to eachother, i will safe you the explanation and try to explain it in our language, porn. Ingredients you need, a fat cock and a tight pussy with big labia minora. Combine these 2 and you get a cool special effect, the labia are getting visible and are moveing with the dick, like its the most perfect pussy around a cock. Ah, just watch and you will see what i mean.