1) A way of reposting tweets on twitter to your twitter timeline.
2) Saying something that someone else just said
Twiterguy1: something awesome
Twitter_gal34: @Twiterguy1 RT something awesome
Guy3: it wont go down!
Guy1: thats what she said
Guy2: thats what she said
Guy1: i just said that
Guy2: i retweeted it