At one point in the episode with sex-ed, one of the "Geeks" asks "Did you see 'Dukes of Hazzard' last night?" "The Dukes of Hazzard" always aired on Friday. Also, the event he describes never happened.
Not likely. "Dukes of Hazzard" debuted in 1979. "Freaks and Geeks" takes place in 1980. I don't think any show can produce enough episodes for syndication in just over a year.
Well, according to IMDB, in 1980 (season 3) there actually were a few "stray" episodes that aired on a Sunday or Wednesday. I'm not saying that the show makers researched it to that level, but it does make it PLAUSIBLE that the students were talking about an episode that aired "last night" on a school day.