"Run" is when the cherry burns a streak down the side of the doobie while you are hittin it. You have to lick your finger and wet the run directly under the cherry(burning part) to stop the run and keep an even burn. Its caused by the extra little bit of paper and resulting fold when you tighten with a dollar bill. Runs can happen even though you rolled a good joint though. Wet the paper at the run and it will stop. Try the breathing trick while rolling. Just breath heavy on it right after you load the weed, before you perform the critical first fold/twist. Makes life easier when your papers are pliable.