By Alice || Edited by Go Ask Alice Editorial Team || Last edited May 26, 2015 

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## Resources

- [Medical Services (Morningside)](/resource/medical-services-morningside)
- [Medical Services (CUIMC)](/resource/medical-services-cuimc)
- [Sexual and Reproductive Health Visits (Morningside)](/resource/sexual-and-reproductive-health-visits-morningside)
 


 

## Cite this Response

###   MLA 9    

 

Alice! Health Promotion. "Why do my boyfriend's balls move on their own?." Go Ask Alice!, Columbia University, 26 May. 2015, https://goaskalice.columbia.edu/answered-questions/why-do-my-boyfriends-balls-move-their-own. Accessed 27, Sep. 2026.

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###   APA    

 

Alice! Health Promotion. (2015, May 26). Why do my boyfriend's balls move on their own?. Go Ask Alice!, https://goaskalice.columbia.edu/answered-questions/why-do-my-boyfriends-balls-move-their-own.

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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?



Dear Reader,

Kudos to you and your boyfriend for sharing your observations and experience — what an opportunity to learn more about how our bodies work.

The cool, subtle vibration you described and witnessed may have been due to testicular circulation. Veins and arteries allow the blood flow to run through the entire scrotum.

If your boyfriend's testicular movements were even more pronounced, then you can thank his cremaster muscle. It gently bungees the testicles to whatever part of the neighborhood they need to hang comfortably in. Another muscle, the dartos muscle, helps move the testicles up and down inside the scrotum. Together, they enable, as Kramer would say, "the boys," to dance.

Testicles are temperature sensitive sperm factories. Sperm need to be kept at a certain temperature to be happy and healthy. When the "boys" get cold, they snuggle up and get warm. Feeling stuffy, they can hang lower to get cool. Just before orgasm, the cremaster and the dartos muscle work as a team to bring the testicles into lock and (un)load position.

Here's another learning activity you and your boyfriend can try that can also get the "boys" to dance just for you. Touch the upper inner portion of your boyfriend's thigh. His testicles will move in the direction away from where your hand is touching. This response is known as the cremasteric reflex, which is a safety maneuver that the testicles perform to stay out of harm's way. When the threat is over, the testicles will come back to a position with which they feel temperature friendly and safe.



   

##  Additional Relevant Topics: 

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