Corrected entry: The joke of Geordi's that Data laughs at, which is established as having been told at some point in "Encounter at Farpoint", mentions the Ferengi, but first contact with that race didn't occur until "The Last Outpost," three episodes later.
Cubs Fan
23rd Jun 2021
Correction: That was the first time they had direct contact with them, but they were aware of their existence. They are referenced by name in "Encounter at Farpoint."