I was showing a friend Twitter and asked users to explain what it was. These are the wonderful answers I got very quickly. It was amazing.
zjjtrans Twitter is an information pool like a network of walkie-talkies.
BeckyMcCray More bad quotes at my Favorite Tweets http://is.gd/45o
verso @apenny more than IM, less than email. But with a megaphone
BeckyMcCray Twitter is the Chameleon of Social Networks. It changes to match your needs at any moment. Conversation, Info, Announcements @sass
zachw http://tinyurl.com/384n2f <-- common craft: twitter in plain english
lisamer Hi to you @penny and your friend. It's hard to describe Twitter; its charms announce themselves through use more than demonstration.
BeckyMcCray “Twitter germinates, where Facebook merely incubates.” from @danlight on SxSW http://tinyurl.com/39zqs3
BeckyMcCray "It's like LinkedIn had a cocktail party." - @NewMediaJim
sioksiok Twitter is an online cocktail party that reconvenes every day.
stephenk @apenny: It is the intersection between text messaging on cells and IRC chat on computers, I suppose. That's how it often is used.