Logrolling (log birling or just birling), is a sport that originated in the lumberjack/log driver tradition of the northeastern United States and Canada, involving logs in a river (traditionally) or other body of water. After bringing their logs downriver, the lumberjacks have a competition to see who can balance on a log the longest while it is still rolling in the river.
The contest involves two lumberjacks, each on one end of a log floating in the river. One or the other starts "walking" (or "rolling") the log, and the other is forced to keep up. The contest involves attempting to stay on the log while attempting to cause the competitor to lose their balance and splash into the water.