Foot odor was the root of Frank’s failed relationship during the Korean war — before acting as Elaine’s “spy” to tell her if her manicurist was gossiping about her, Frank recounts the story of falling in love with a Korean woman, which ended with a bad breakup because he refused to take off his shoes in her home. Luckily, they were able to rekindle their love several years later at the end of the episode, but it didn’t take long for them to start arguing again.
Source : https://www.distractify.com/p/frank-costanza-quotes