Jugum penis is a part of a boy's private area called the penis. It's not something you can see from the outside, but it's inside the penis like a little bump.
When a boy's penis gets bigger, the jugum penis can help keep the penis straight and stable. It's kind of like a little hook on the inside of the penis that helps hold everything together.
So just remember, jugum penis is like a little bump inside a boy's penis that helps keep everything in place.