On Thursday, a man threw on a Transformers mask, grabbed a fake gun and a knife, and went into a Fresno Starbucks.
He walked up to the front counter and threatened the clerk.
That's when Cregg Jerri stepped in.
The 58-year-old customer walked up behind the armed robber and repeatedly smashed a chair over his back and head.
The two engaged in a fight, during which Jerri was stabbed in the neck. He was able to get the knife away from the robber and stabbed him multiple times.
The robber escaped, but he was soon tracked down and arrested.
Chief Jerry Dyer of the Fresno Police Department said, "It was incredibly heroic and the way most people would think that they would respond but may not have the courage to respond."
All while wearing flip flops.
Read the full story at CBS San Francisco