The foreskin must move down from the head of the penis to the shaft, and without this lubrication, the move may be a little slower or may be even a little painful.
Smegma is completely natural and useful.
It is produced all your life, but in greater quantities during the teen years. Smegma, despite its beneficial attributes, also has it down sides . If smegma accumulates under the foreskin, it becomes, stinky and unhealthy. When you're in the shower, take some time out to gently pull back your foreskin and clean the area between the foreskin and your head, called the foreskin cavity, gently with soap and water, and rinse well. Also, don't allow foreign materials, such as semen, urine, dirt, powder or sand, to hide under your foreskin.