The Loogie (The Boyfriend, Season 3, Episode 17)
Kramer and Newman believe that Met’s great Keith Hernandez spit a loogie on them after a game in the past, which leads to some investigating by Jerry.
This re-enactment of JFK’s assassination may have been too soon, but it was spot on in terms of comedy. Jerry finds out based on angles that there must have been another spitter, which means Keith was innocent, and Kramer and Newman have reason to hate him.