Since beginning college in September, I became more sexually active, and have been having sex or some sort of sexual activity about once every other day, though weekends I sometimes have sex three times. =)
Anyway, a couple times I noticed that after sex, my testicles would hurt for about an hour after sex. This only happens after intercourse though, never after oral or manual stimulation. It's not blue balls because I orgasm each time, but its different from how the penis is generally sensitive after sex. I feel it in my testicles, and they can be temporarily relaxed by gentle massage...It doesn't happen all the time, but when it does, it's extremely uncomfortable.