"America's Got Talent" star Zac Gordon ... aka Horse ... aka the guy with iron testicles ... is lucky to be alive ... after smashing his car into a tree while trying to avoid striking a deer, TMZ has learned.
Horse -- who became famous for allowing people to bash him in the scrotal-region on AGT -- tells us he was driving in Harrisburg, PA Saturday when a deer suddenly ran out in front of his car. Horse says he jerked the wheel, trying not to kill the animal ... but lost control and went careening into a tree.
Zac says he hit the tree so hard the car flipped over -- "I legitimately thought I was going to die."
An ambulance rushed to the scene and hauled the AGT star off to the hospital. He was released later that night with a possible concussion, sore neck and scratches ... but luckily no major injuries.
"I'm just glad to be alive," Horse tell us.
Now, here's Zac crashing into other things: