I heard my rabbi say that you’re not supposed to say Good Night on Friday night, but rather should say Good Shabbos instead. First of all has anyone else heard this (or was it just a joke) and if so then where does it come from?
See Mishneh Berurah (307:5) where he quotes the Sheloh which says that when meeting someone on Shabbos one should not greet him in the weekday fashion, "good morning", rather he should say "good shabbos" in order to fulfill the mitzvah of "זכור את יום השבת."
In the sefer Korban Ani (לר' יעקב קטינא) parshas Breishis he quotes the מוהרי"צ מראזדיל that says the reason why do not say 'good night' on Friday night is because on shabbos there is no night rather only light. Therefore on Shabbos it doesn't say "ויהי ערב ויהי בוקר". Like it is also mentioned referring to Moshiach "לילה כיום יאיר כחשיכה כאורה". (quoted here)
(The רמ״ע מפאנו (Yonas Elem 38) writes that this is the deeper reason why there is the repetition of the Amidah on Shabbos night, something we usually only do by day.)