About 10 years ago I was doing BB bent over rows... it was really cold in the gym and my balls were very tight.  While doing the BB rows I felt a slight pop noise in my balls... no pain though.  Next day after I had sex with my girlfriend there was brownish-red blood all over the place.  I got really scared.  I had sex again the next day and it was still brown, but not as dark.  It cleared up in about 10 days.