My theory is that [Tinfoil hat] there was a ketchup packet lodged in the rolls of his neck from lunch that day, and it popped when he was startled by the gunshots. He was unaware that he lost the condiment there, and it was unintentional. He genuinely thought it was blood until it trickled into his mouth, after which he raised his fist in relief, yelling “Heinz Heinz Heinz” to the crowd. [/Tinfoil hat]