Mesmo em contextos informais seu emprego deve ser sempre "jocoso"...
O uso de said person
preenche esse requisito. Indo ao site Wordreference, encontramos explicações feitas por falantes nativos do inglês, que confirmam que said person
é uma opção válida para se dizer dito cujo
em inglês. Então, sem mais delongas, mas ver o que eles afirmam:
Trecho da pergunta no Wordreference
- Getting a new kidney is a really big deal. There's waiting lists, lots and lots of forms to fill out, and if I can't find another kidney real soon, I'm dead meat. Yeah, well, maybe, just maybe, there's a person out there who cares about you so much that said person would be willing to give up a little piece of himself to save your life.
- USA - UK: Said is often used a determiner in its own right, especially in legal documents and reports. The speaker is using "legalese" for effect, humorous or otherwise.
- USA: The Google Ngram Viewer shows that "said person" has "the" in front of it about 50% of the time.
When it occurs without the article, we can say that "said" is itself acting as a determiner (alias a demonstrative adjective).
Either way, this use of "said" is characteristic of archaic, formal, legalistic language,
So there's a humoristic effect when it occurs in an informal conversation along with "big deal", "lots and lots", "dead meat", etc.
Como se pode verificar nos trechos acima, eles mencionam que said person
pode ter um tom (jocoso).