1. (noun) A dancing simulation game. Originally from Japan, the point of the game is to step on 4 flashing panels (up, down, left, and right) in time to music that the game plays.
2. (verb) to play Dance Dance Revolution.
1) I got bored the other day, so I invited some friends over for some DDR.
2) We didn't feel like doing anything special, so we just chilled, DDRed, and played cards all day.