Meet John Hetlinger. Retired aerospace engineer and Navy pilot, he has dedicated his golden years to something even more badass than launching the Hubble telescope and beating the Nazis: hard rock. Hetlinger may have retired as an engineer but is a fully active karaoke artist, taking on America's Got Talent singing metal with the energy of someone who has seen some real sh*t.

Hetlinger shocks Simon Cowell, who has basically seen it all at this point, with an impassioned take on Drowning Pool's "Bodies." The notoriously sassy Cowell is rendered speechless.