Patent US6368227 - Method of swinging on a swing - http://www.google.co.uk/patents...
Yeah baby... yeah... - Johnny
"Lastly, it should be noted that because pulling alternately on one chain and then the other resembles in some measure the movements one would use to swing from vines in a dense jungle forest, the swinging method of the present invention may be referred to by the present inventor and his sister as "Tarzan" swinging. The user may even choose to produce a Tarzan-type yell while swinging in the manner described" !!! - Ross Miller