Two bros from the U.S. of A. were gored at this year's first Running of the Bulls in Pamplona, Spain ... and one of them took it square IN THE NUTS.
Hospital officials say the 29-year-old's scrotum injury isn't considered serious ... but any damage to the ball bag is no joke.
The other American gore victim is fine too ... but one Spaniard needed surgery on his head and leg. The identities of all three men haven't been released.
What's really crazy: Tourists get skewered at this religious rodeo every year ... and keep comin' back for more!