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I can think of like 50 off the top of my head. That's a pretty generic, common "bully" character quote. Do you know what it was from? Like was it live action, animated, etc? When did you see it? I know people call Mr. Miyagi "old man" in a derogatory way in Karate Kid, but again, your question is pretty vague.
I forgot, I just remember the way it was said. I did see a Nostalgia Critic episode of Karate Kid though so maybe it was from there.
My first thought was the scene in Mighty Morphin' Power Rangers where the evil Green Ranger is tearing apart the Command Center and Zordon says something like "I can protect you" and the Green Ranger says "You should worry about protecting yourself, old man!"
I'm thinking of something like "What you gonna do about it, OLD MAN!?" It's more like in italics than all caps though, like with disdain. That's probably not an exact quote and it might not even be the correct phrase, but do you know any show or movie or video on Youtube with an animation or something where someone says something like that with "Old man!?" at the end of the sentence?