|you can actually buy soap shaped like a brain here. (It smells like bubble gum!)|
|Soap + shaking = trapped oil (source)|
|Cell membrane (source)|
You can wash your skin with soap because the living skin cells are protected by an outer dead skin cell layer. Though if you soap up too much, you can actually dry out yours skin by stripping it of lipids faster that they can be replenished. See "How much should you shower" for an excuse to stay in bed tomorrow morning rather than get up and shower.