In an attempt to draw out rival mobster Virgil Sollozzo and the rest of the Don's enemies, Luca Brasi pretends to switch allegiances and meets with Bruno Tattaglia. Luca was always cautious, as he brought a bullet-proof vest with him everywhere, but it would not save him this time. Sollozzo stabs Luca's hand with a knife, pinning it to the bar as Tattaglia's henchmen garrottes him from behind. No easy task, as you can tell from the expression on the henchman's face. Luca is a big man and isn't going to go down without a fight. Another iconic death from a iconic film.....
Later on, a message is later sent to the Corleone family: a fish wrapped in Brasi's bulletproof vest. The meaning is made clear to the Corleones.
"It's a Sicilian message. It means Luca Brasi sleeps with the fishes."