I believe the origin of it uses old legal jargon (possibly just TV-legal, not actual legal) such as “The court hereby alleges that one John Doe did, on the night of September 29th, with malice aforethought…” (Where that comes from, I have no idea. I suspect “Legal” could give you a better answer

(but not a good one.) In the case you’re asking about then it’s a form of humor that uses unnecessarily serious language to discuss a trifling matter. Rather than Jerry just answering the question “Tim Whatley” he uses a (pseudo?) legal construction “One Tim Whatley” as if he is filing charges against Tim for re-gifting.

I believe the origin of it uses old legal jargon (possibly just TV-legal, not actual legal) such as “The court hereby alleges that one John Doe did, on the night of September 29th, with malice aforethought…” (Where that comes from, I have no idea. I suspect “Legal” could give you a better answer

(but not a good one.) In the case you’re asking about then it’s a form of humor that uses unnecessarily serious language to discuss a trifling matter. Rather than Jerry just answering the question “Tim Whatley” he uses a (pseudo?) legal construction “One Tim Whatley” as if he is filing charges against Tim for re-gifting.