Can men wear jocks as underpants?
They could, but most don't because jock straps can be uncomfortable. They are designed to hold the testicles close to the body for protection, but that keeps the testicles warmer and may interfere with sperm production. Also, since there is no back side, you have to be extra careful to clean up after having a bowel movement. Any trace stool left will stain your outer clothing which is usually harder to get out. Overall, jock straps work well in an athletic situation, but tend not to be useful as general everyday clothing.