There's no such thing as fun for the whole family.

Seinfeld’s line plays on the marketing cliché “fun for the whole family,” puncturing it with the observation that families rarely share identical tastes, ages, and tolerances. The humor comes from treating a sentimental promise as an empirical claim and then rejecting it as obviously false. Implicitly, the quote also comments on how entertainment and leisure are often sold as universally appealing, when in practice they involve compromise—someone is bored, annoyed, or merely enduring it for someone else. As a piece of stand-up-style skepticism, it fits Seinfeld’s broader comic persona: attentive to everyday language and quick to expose the gap between public slogans and private experience.