Why Testa's Knife-Walking Act Was Unlike Anything the AGT Judges Had Ever Seen

Sometimes the America's Got Talent Judges come across an Act even they haven't seen. Granted, it's rare— but remember, this is a show that features everything from teenage opera singers to dogs that do backflips. Simply put, Judges Simon Cowell, Howie Mandel, Heidi Klum, and Sofía Vergara aren't fazed by much these days. 

However, they were very, very fazed by Testa, a danger Act who did something Klum straight-up said she had "never seen." So, what did he do, you ask? Well...he walked on knives. Literally. 

Honestly, we can't do this Act justice with a description. Just watch Testa's performance in the video, above, and prepare to be amazed. And terrified. And impressed. The Judges were all of these things in equal measure—and you could see it on their faces. 

"I have a weird relationship with Acts like this because I love them and I hate them," Vergara said. "It's like I want to see it, and I don't want to see it. This was giving me all of those feelings, and it was amazing." 

Acts like Testa's must be what Klum was talking about when she said judging AGT is like a "rollercoaster of emotions." 

"Every day is new and different," she told Access Hollywood "I mean, yes, we [the Judges and Host] might be the same, but you see all these crazy, different people on the stage. We're having the best time. I always call it a 'rollercoaster of emotions,' because a person comes and they're singing. The next is an aerialist. The next one is a contortionist or a comedian. Everyone has a story to tell because they're real people. They're not actors. This is not a movie. This is real life. It's always fun to hear the stories...it never gets boring." 

Never gets boring indeed. Testa advanced to the next round of AGT, so you'll have to tune in Tuesdays at 8 p.m. ET on NBC to see how he does.