Hey Alice,
I have a weird question. My boyfriend and I were talking and he told me that men's balls move on their own throughout the day. I did not believe him so he showed me. He got undressed and laid back on the bed and told me to lift his penis and watch real close. I did and unbelievably, his balls moved. It's like they vibrated kind of like a heart beat. It was so cool. What makes a man's balls move alone?