I haven't actually watched all the way through Seinfeld before. I tried getting into in college back in 2006, when I was really enjoying Curb, and I don't know how far I got, but probably fizzled out around season 5. I know there is one episode involving the Puerto Rican flag that I never saw because I was in Alabama at Space Camp when it aired. It was somehow offensive to people and wasn't re-run on TV again. No other way to watch the shows back then, so I never actually saw it, but I'm excited to see something new. I recently watched through all of Curb in prep for season 12's launch, and I noticed there are several re-used storylines from Seinfeld that appeared in Curb.
- Elaine complains about someone who takes a sip of their drink and always says vocally "tssss AHHHHHH." That was used in an episode of Curb where Suzie started doing that, but Larry had to tell her to stop it.
- The Car Periscope idea was mentioned in Seinfeld by Kramer as a great idea. Larry invests in one as a concept from a guy who has a homely looking wife, which Larry and Jeff thinks makes him trustworthy.
- The ladies frames on George, same sort of thing happened to Larry on the season 12 opener.
I'm sure there are plenty of others, but those ones stood out to me. A lot of phrases are re-used, but they work with the Curb stories, and are more like easter eggs to be noticed than something shoe-horned in somewhere they don't belong.
Anyways, I'm at the beginning of Season 8 now, and just watched the Bizarro Jerry episode, which was great stuff.
"Feldman and I gotta get down to the library." - nice guy from White Collar
"Why?"
"To read."