You can tell if your ball has dropped if you can see and feel the balls or testicles in your scrotum.
Your scrotum is the pouch of skin that is below your penis.
If you cannot see or feel your testicle in the scrotum then it may be be undescended.
When the testicle is undescended it means one or both testicles have not moved down from the abdomen and into your scrotum during development.
If you can feel your balls or testicles or see them in the scrotum then the balls or testicles have dropped.
Doctors will often diagnose undescended testicles during a routine physical examination, especially at birth or shortly after.
If your testicle can be felt, even if the testicle is in the groin, it's considered to be palpable and if it cannot be felt then it's considered impalbable.
In some cases a testicle may move up into the groin when you're cold or scared although then it will move back down on it's own and this is called a retractile testicle and is not often a problem.
An undescended testicle stays up and does not move back and forth like a retractile one.
And if both of your testicles are undescended, your scrotum will appear small and flat and if only one testicle is undescended, your scrotum may even look lopsided.