1)can patent urachus suddenly occur out of the blue at age of 20 in men?2)can poking ur belly button punture a hole that lets urine leak out?

Yes, but is so rare: The urachus or its remnants goes away when one is a young baby. It is possible, but very rare, for a urachal cyst to remain and get diagnosed in adulthood. That can happen if the cyst gets infected and appears as lump under the belly button, maybe with some pain and pus discharge. The infected cyst can be treated and surgically removed. If someone has no cyst, poking his navel will not leak urine.

1) Yes. 2) No.: A patent urachus is a still open congenital connection between the umbilicus (bellybutton) and the dome of the bladder. Poking your bellybutton will not cause it. A patent urachus is manifested by urine leaking out of the bellybutton or infection of the abdominal wall or bladder. Although we usually see it in younger children, it can become apparent in an older child or adult. Surgery is needed.