1. A car with one headlight clearly dimmed and the other normal.
2. A game played in the car - when one sees a "dimdoodle" one smacks the roof of the car and yells, "DIMDOODLE OMG LOLOL" and the last to smack the roof takes off an article of clothing. Often played alongside <i>PERDIDDLE</i>. Rules vary car to car.
And suddenly, seemingly out of nowhere, a truck is spotted in the rearview mirror with one headlight much dampened (so to say.. less bright). Quickly the spotted yelps, "DIMDOODLE!" and smacks the roof of the car, and the others in the car respond as quickly as possible by doing the same. The last to hit the roof perhaps utters some profanity and removes an article of clothing.
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.