elevator pitch n. a very short persuasive speech, usually delivered impromptu. Also elevator speech. (source: Double-Tongued Dictionary)
Further reading
Brenna, a nurse in Rapid City, South Dakota, says she was on a hospital elevator full of people and when the doors opened and someone in the back was trying to get off, she piped up with One side or a leg off!, but no one understood that phrase. It...
A young caller from the Hudson Valley of New York wonders about his grandmother’s use of stemwinder to praise a speech she thought was excellent. In the early 1800s, people used pocket watches that had to be wound with a tiny key. Once someone...
Pithy definition and good contexts, but two minutes is a long elevator ride!