Quotable bit on a movie poster

• Nike's is 'Just Do It'
• Entertainer's signature
• Identifying phrase
• "Good night, and good luck," e.g.
• Something funny in setting of gelatin
• Genitals mostly involved as point of joke
• Catchword; slogan

Wikipedia Word definitions in Wikipedia
In entertainment , a tagline (alternatively spelled tag line ) is a short text which serves to clarify a thought for, or is designed with a form of, dramatic effect . Many tagline slogans are reiterated phrases associated with an individual , social group ...

Wiktionary Word definitions in Wiktionary
n. 1 The punch line of a joke. 2 (context computing English) A pithy quote habitually appended to a signature, used as an advertising slogan, etc. 3 A line attached to a draft of cargo or a container to provide control and minimize pendulation of cargo ...