The white dirt inside the foreskin is called foreskin scale, which is produced by the inner plate of the foreskin. This is because there are certain sebaceous glands under the skin where the inner plate of the foreskin and the head of the penis meet, which constantly secrete yellowish lipid-like substances that mix with the dirt shed by the skin and stained urine to form foreskin scale. Over time, if not cleaned in time will accumulate thicker and thicker, it will become a flaky or blocky white tofu-like object that can cling to the skin in this area. If the area is not cleaned in time, the foreskin scale will accumulate thicker and thicker. When the foreskin is too long or circumcised, the foreskin scale cannot be discharged and gradually forms a strange smelly solid. This is a good place for bacteria to grow and can lead to inflammation of the head of the penis and the inner plate of the foreskin, causing recurrent episodes of glans penis.