15 years old, the penis is very thin and short. Like a child, my classmates laughed at me. What should I do?

Are you worried about being only fifteen years old? Medically speaking, fifteen years old is not an adult. If you are still so short as an adult, that is a problem. Generally, the penis erection of adults is not less than 5CM, which is within the normal range. If you are afraid of classmates' jokes, go to the hospital. If the doctor says it's not normal, since you are still young, there must be a way to solve it.

If in doubt, please ask.