There's not a lot here in the way of positive messages. Characters are petty, selfish, and often shallow, and lying, cheating, and gossiping are frequent plot elements.
Some slapstick pratfalls and physical violence -- nothing serious, and always played for laughs.
Lots of discussion about dating. Plenty of innuendo and funny discussion of sex (sometimes veiled, sometimes less so). One episode centers on a birth control device; another on masturbation (though it's never referred to directly). One episode revolves around trying to guess a woman's name that rhymes with a part of the female anatomy (possibilities include "Mulva" and "Dolores").
Words include "damn," "ass," "hell," "bitch."
Some mention of specific brands, especially candy (Junor Mints, Jujubes, etc.). Jerry uses an Apple computer and is a breakfast cereal fiend.
Drinking, Drugs & Smoking
Occasional wine drinking in restaurant or party scenes. Cigarettes appear in some episodes, though usually for comic effect (Kramer smokes and drinks at the same time in one episode). Speculation about drug use, but none shown.