Gents, if you inexplicably feel like you got kicked in the junk, talk to a medical professional immediately.
I suppose we should tell him.
It’s when one or more of your thingies twists around on the strings they dangle down from.
Those strings are a duct (viaduct? Vy not a chicken?) and an artery and a vein.
Twisting them together is like pinching a garden hose, it cuts off the flow, strangling the blood supply to “Them”
“They” will croak without a fresh supply of oxygenated blood.
“They” will let you know they are NOT HAPPY with this prospect.