shit my balls off
Being so surprised to the point that you inevitably shit so hard your testicles come out.
Dudebro: Dude I went sky diving yesterday.
Broseph: How was it?
Dudebro: The main parachute didn't work, I was so scared I shit my balls off.
Broseph: How was it?
Dudebro: The main parachute didn't work, I was so scared I shit my balls off.