Automatic penis erections (no sexual stimulations involved)

My bf has an unusual penis erection situation. Regardless of what he's doing like eating or sleeping or reading - nothing sexual to stimulate, he gets erection and it happens often all day. I wonder if he has a medical condition similar to some women who have orgasms easily regardless of what they're doing in their daily routines (chronic clitoris stimulation?). It sets off by vibration or slight movement. It seems that it is the same for my bf. What is the condition or disorder called for automatic penis erection?

Btw, he's 49, almost 50 and he said he has this all his life and doesn't know why. He thought he's one of the rare lucky men who can get erections easily, even at his age.

Will it be problems for him down the road if it's not treated? Please advise.

Thanks!