Anyone who has ever taken basic Physics, which is a graduation requirement at MIT, can tell you that friction is the arch-nemesis of motion. Friction always opposes motion, and whenever bodies are in contact, a la intercourse, there will be friction. Some friction is a good thing, but too much can lead to painful consequences. When that happens, the result isn’t pleasant for either partner. Usually there’s a chain reaction: if a partner goes dry, the other partner goes soft. Many a virgin has botched an attempt at losing it because of too much friction.