This is best done on mats or soft grass. The group lies down on their tummies about 1½' apart, arms outstretched, face down.
The performer kneels at the head of the line by the hips. As they yell "surf's up", the line begins to roll, and the performer push themselves over the "hips". As everyone rolls, the performer is pushed to the end of the line.
From the Ghost Ranch Ropes Course Manual, by Dr. Sylvia Shirley.