Kick a man when he's down.
Because of me, John dies at the end.
What am I?
I had the idea to this the last time I had some of those amazing/nasty cylinders for dinner.
Man, do I love food. Especially the 8 (no not that one). Get it up!
Could it be
soy sauce?
Kick a man when he's down.
"Kick a man" => Kikkoman, a popular soy sauce brand
Because of me, John dies at the end.
A mysterious serum called 'Soy Sauce' plays a major part in the film
I had the idea to this the last time I had some of those amazing/nasty cylinders for dinner.
Egg rolls?
Especially the 8 (no not that one). Get it up!
No clue what this is referring to
Partial:
Kick a man when he's down
It's a phrase which means to hurt someone who is already weak.
Because of me, John dies at the end
John dies at the end is a movie released in 2012. This matches with the clue you will see when you edit the question.
What am I?
This maybe suggests that the solution is a thing rather than a person.
And
But I don't know how this things are relevant to each other or even they are relevant to finding solution because there is the trivia tag in the question.